new exhaust low idle

[T(ra)-VIS]

I just got new exhaust on my car. I had to get a new cat because the old one was falling apart inside so i got the cat and the whole pipe all the way back to the muffler. The guy said that because the shit from the cat was clogging up alot of the flow before that I might need to do a tune up on it now. I noticed that a couple times when i start my car and its warm the idle drops to 500 and the car sounds like its gonna die. If i hold the gas lightly for like 5 seconds the idle goes back to normal. Its only done it twice but I'm wondering what it could be making it do that. One person said it could be the O2 sensor or the throttle position sensor. Does anybody else have an idea? Has this happened to anyone else ?
P.S. If anyone in the lowermainland B.C. needs exhaust done go to "Muffler Man" on kingsway in new west. Thats where I got mine done and they were really nice, fast, did an awsome job and were pretty cheap.

[Deep]

I'd check the harness on the 02 sensor first to see if its plugged in right, then as he suggested, have a look a the plugs to see if they're fouled. If all that fails, you may have a tiny exhaust leak.

[lloydjv]

I don't know if it would help, but have you tried to remove the ECU fuse to reset any codes that may be present? Just a thought. Could be an EGR malfunction or open loop configuration.

[T(ra)-VIS]

yeah, i was thinking of just unhooking the battery for a few minutes. I know in newer cars it re- sets the computer then you run the car so it can re set the idle. I can give it a try cant hurt nothing but im not sure if it works on cars as old as mine. It's an 87

[turbo_GT]

wha'ts the size of your piping and the muffler??that could be a problem..not enough back pressure...you can also adjust your idle...back to where you want it...

[T(ra)-VIS]

The piping is 2" from the cat then 2/14" at the muffler. It hasn't done it for a couple days now so maybe it was just a computer adjustment that has been re-set. I guess I'll see if it keeps running good.