I would check spark plugs first

 

Plugs are a little over a year old but I'm not sure what brand. I'll check them next weekend. I read plug wires could be an issue. They look a bit old. IAP, EGR and a temp sensor may also cause it.

 

Check your high tension cords, air filter and spark plugs (& plug gaps). The 1994 2.2L Camrys do NOT have a MAF sensor. They utilize a MAP sensor mounted near top center of the firewall. Check all your vacuum hoses as well for leaks, as that will also cause you problems. Make sure your PCV is working properly and not clogged. I had this exact same issue a few years ago, and new high tension cords fixed the problem. I used NGK (8762) blue wires and she’s been purring ever since.

 

I actually found your thread just after I started this thread. I have a set of these NGK's in my watch list on eBay. They've really gone up at Amazon since your post.
My air filter is still like new. I'll inspect the other things while I'm at it.

 

I had a chance to check most of everything I wanted except the IAC. I need to remove it with the throttle body and then take it off. It looked clean looking at the throttle plate and opening it. The plugs, air filter and EGR were fine. The EGR was a real PITA to remove because there's not much room to fit a wrench on the pipe that attaches to it. I managed to find an adjustable wrench that fit just enough to get an inch of movement. It was fairly clean and the vacuum diaphragm worked like it should.
The plugs are NGK's and looked fine with just a little white deposits. The distributor cap and rotor looked like new inside. The plug wires look old and will be replaced.
I found a rubber grommet on the side of the air filter box that had nothing attached to it. I'll have to find out what kind of hose or pipe connects to it. I plugged it for now.
The engine otherwise runs really good and idles very smoothly. I'm about 800 miles into my last oil change and still looks clean. It doesn't seem to burn any oil between 3K-4K oil changes. So far I'm happy with this cheap car purchase I made a year ago.

 

I found what's missing from the air cleaner. It's some kind of air flow sensor according to a youtube video I found. I have to find what happened to mine. Could it cause any running issues?

 

That sensor you are missing, per the diagram below, is an inlet air temperature sensor. If it is missing, your check engine light would be on. You said your check engine light is not on. Is the lamp burned out? Does your check engine light come on momentarily when starting the engine?

Without input of the inlet air temperature, your engine will not run well.

 

The light does go on momentarily like it should. Maybe it's hanging in the engine bay somewhere near the air box? I'll have to check tomorrow.

 

I found the sensor hanging off the cable a way down below the air box. That's probably why it wasn't throwing a code or causing running issues.

 

Might be why it didn't throw a code. Not sure about the running issue. Put it where it belongs and go from there.

 

I cleaned it up and stuck it back in where it belonged. I haven't driven it yet but I don't expect any difference. I have NGK plug wires coming.

 

Got the plug wires and installed them yesterday. I didn't have a chance to drive it but my wife did. She said it drove fine. Both of us drive the car since it's currently our most fuel efficient car. We also don't worry too much about leaving it somewhere when going shopping or whatever.

 

I've been driving the Camry the last few days. I had a random stumble again while I started off from a stop light. It wasn't too severe but enough to get my attention. I guess maybe I need to check the IAC? It looks like the best way is the remove the throttle body to get at it. I'll need to find time to pull it since I'll need to order new gaskets from somewhere.

 

My wife drove it a few days and she noticed the stumble a few times but was fine most of the time. I'm still waiting for the gaskets to arrive so I can clean the throttle body and IAC. I have OEM ones coming from my local dealer but even they had to order them.

 

Yesterday I removed and cleaned the throttle body and the IAC. There was some carbon residue on both of them. I also sprayed some cleaner into the intake as well. I drove it to town and back today. It ran fine as I expected it to. We'll see if this takes care of the issue. I wouldn't know where else to look if it doesn't.

 

Sounds promising. Let’s hope it continues to work well.

 

Just an update after a week driving since the cleaning. It's running and driving fine with no stumbling so far. The idle seems a bit lower, around 750 rpms in drive. The engine's vibration is a bit more pronounced. I'm sure it needs new engine mounts but I can tolerate it for now.

 

The idle speed of your engine should be 700 +/- 50 RPM when warmed up, no accessories on, transmission is park or neutral. Yours is at 750 RPM when in drive, which means it would be a bit higher if it was in park or neutral. So your engine is running a bit too fast. That may be part of the reason for some vibration - it is working too hard when in drive at that speed.

 

The RPM's used to be closer to 1000 RPM's at the stop light. I hadn't paid attention to the idle speed in neutral before or after. There wasn't much vibration when it was near 1000 RPM's.
I didn't mess with with the position of the IAC when I cleaned it. I've read moving it from the factory setting will change the idle speed.

 

So after a few weeks of driving it runs fine and hasn't stumbled as noticeably as before. It still occasionally hesitates very mildly but not to the point it did before like it was about to stall. It still idles around 700 to 750 rpms in drive. The rpms pick up slightly in neutral, maybe no more than 800 rpms. To me this seems good enough. I've yet to check the fuel consumption to see if it's changed.

 

It's still happening. My wife had it happen a few times while driving it and it happened to me a couple of times the last two days. It's annoying that nothing comes up on the CEL nor when doing the diagnostics with the CEL.
I would figured it out long ago if this would have been a car with with points and carburetor.
At this point I don't know what else to change except the distributor cap and rotor.

 

Have you visually inspected the rotor and the contacts inside the cap?

 

see post #6, " The distributor cap and rotor looked like new inside."

 

Exactly, There was no burning, scuffs nor corrosion on any of them. So far I feel I have just been throwing parts at it. An Italian tune up did nothing either.
If it had a carburetor, this is the exact same symptom of a failing accelerator pump or a failing condenser.

 

Try running a couple rounds of a good fuel cleaner through it. Something like Redline or Techron

 

I'm willing to try it. I've cleaned the throttle body already since I was in there cleaning IAC. I wonder if it's being caused by a bad spray pattern from an injector? I really don't want to mess with them unless it becomes really necessary.

 

Always a possibility. Any CELs?