1989 22re 4x4 stumbles and jerks

[Tool Wizard]

I have a 1989 4x4 truck with 22RE.
Problem: The motor stumbles and misses and starts to cut out. This happens when at operating temp only. Also only when driving at a constant steady speed. Press or release the gas pedal and it runs smooth with good power. Speed or gear selection doesn't matter.
What I have done to the motor: New cap, rotor, plugs, wires, Accel coil, distributer, TPS(2Xs), all new vacumm lines, repaired exhaust leaks, cleaned throttle body, cleaned injectors(new seals too), check coolant sensor(is in speck with chart curve) Timing is set at 5 deg with jumper wire in place. Has a fair to good idle. Check engine light has come on a couple of times. Code 25 and 26 same time no others. Reset by pulling fuse and have pulled neg battery terminal. Truck will go for weeks without throwing a code but the stumble still is there always. Sometimes runs really bad and I wonder if I can get to where I am going then it just smoothes out for a while and runs fine.If ya keep your foot moving on the gas pedal it runs perfect always.As soon as you hold the pedal still or steady at speed it will stumble. I am thinking 02 sensor but have never gotten a code for it. 25 = lean signal, 26 = rich signal. I have read all the posts on the 22re in this forum. Lots of great info......Thanks in advance for any help.
T.W.

[Flash319]

It sounds to me like a computer thing. I would check your MAF sensor and see that it is not jammed or somthing. This is one of the most inportant sensor in the Toyota fuel injection map. Just open up the airbox and move the flap with your finger. It should be easy to move. The vacuum of the engine must move this.

[WKOBE88822]

check out this tread this was my problem with a similar problem to the one you are talking about http://www.toyotanation.com/forum/t14957.html

wayne

[Tool Wizard]

I have checked the MAF by pushing the door. It seems smooth and is clean. I can swap it with a friends to see if it transfers the problem.
I had already read WKOBE's post and checked the wireing when I cleaned the injectors.
I only had gotten code 25 and 26 together but that had been a while now and I am not getting any now. The problem is still there.
What year model computers are compatable with the 1989 one? I have 2 from an older one 86-88 not really sure. The plug in connectors on the box are yellow.
I will try different computer if I can find one and MAF sensor.
Thanks again.

[Tool Wizard]

Well it is not the computer. This problem is happening at any temperature now. It's much worse when outside air is cold in the 20's or 30's . Athough it will still miss and stumble when the outside air is warm 60's and up. It is much worse when cold. I haven't found a MAF to exchange with yet. No codes or check engine light since I started this post.
TW

[kuto]

sounds like the TPS to me, check it out

[Tool Wizard]

Thanks for the reply Kuto, I have put 2 tps sensors on already. I found a MAF in a bone yard for 20 buxs today. I found E2 to VS pins on the sensor (mine) to be open and not in the 20 to 400 ohm range as the book said. The one I bought is in speck with the airflow meter resistance chart. Gotta love a repair manual. I took about a 10 mile ride after changing the maf out and the truck run alot better. No missing or stumbling. It was running like crap before I changed it. I will know for sure over the next few days.
TW

[RICHIE]

check the egr vacuum modulator valve,could be going bad and also be sure you arent getting leaks around the new hoses.he replaced them also and the were a little loose. so when you tocched them there was a vacuum leak created.