My 92 SSEI idles rough only when it warms up but it is sporadic. I took to gm Dealer and had them perform injector balance test and fuel pressure test. They said nothing wrong with engine. I looked at printout data from test and everything looks normal. Morons tried to sell me new engine and transmisson mounts for $1300. and said that causes engine to idle rough.
Anyway I replace three coil packs (they were cracked) and wires and IAC and cleaned throttle body new 02 sensor as well . No change this problem started and three years ago and is now getting worse. Tach shows steady RPM, never stalls, Motor runs fine in every other sense, even great gas milage 36 Mpg on hwy 70 mph lots of power. Car has 340,000 Kms but runs great other than this annoyance.
Dealer is useless I am not wanting to perform shotgun mechanics "too Expensive" for that guessing game.
anyone have similar problem Cure??