Fires fine, cold idle works every time. No change with brake pedal pressure, no known vacuum leaks. Intake plenum clean, EGR clean.

Now, once warm, idle is one of two things: normal (~800rpms and steady) or low (~550rpms and steady). Low idle is very rough and sputtering, but doesn't fluctuate. Still picks up fine from the stop sign. Sounds like crap and sometimes (rarely) dies. Park for a trip to the store or something, come out, may idle fine, may be rough. No rhyme or reason.

Ideas?

 

check TPS? might be out of adjustment, or shot
plugs?
clogged cat?

abe is sure to chime in on this..

 

TPS is on the list! Cat, plugs, etc. have about 1500 miles on 'em, so possible, but not likely. Good call, though.

 

22RE's have alot that can contribute to a strange idle, its best to go with the cheap basics first

 

My '93 does this very rarely, maybe every 1K-2K miles and hasn't done this since the temperature dropped below 0*F in November. Check the coolant temperature sensor, make sure the coolant is at the right ratio, and no air is present in the cooling system. Check what 4bangingRunner said as well

 

My idle changes all the time. If i drive 10 miles on the freeway it will idle at 750. If I go for 100 miles it will stick at 1000 or so. Seems like giving it a rev or two will lower the idle. I think the dash pot is a piece of crap. And isn't functioning properly.