Bofore you go for a new prom, check the number on the one installed as of now, so you have something to throw at the counterman when you go into the dealer.
AND, before that, be sure about vacuum leaks/unmetered air.
Many times a vacuum leak was the issue. The upper intake to lower intake seemed to be plagued by this. New gaskets would usually cure it.
Be certain the PCV system is working and the valve shuttles properly
Check the EGR, take it off and clean it , to be sure it seals.
Clean the throttle body and the IAC pintle and seat.
Did you perorm a minimum air rate adjust ment?
Last but not least is the MAF.. Be careful with that one. Take it off, clean with a dedicated MAF sensor cleaner ONLY. I sometimes very softly use a Q Tip to clean the thermistors inside as they get blanketed with media from the paper air filter.
It is a very very good idea, after cleaning a MAF to wait about 15 minutes before plugging it in, especially on one of those old "hotwire" sensors. If not it can damage the internal circuitry from excess current flow through it to heat the wire.
If you have done all these things.....then off to the chebby dealer
Oh one other thing. If you have an OBD1 scanner you should check the data stream to be sure the O2 sensor isnt causing the system to run lean, or drop in and out of closed loop at Idle speed.O2 sensors are a maintenace item , like a spark plug. Maybe try that first if it looks original. It may help.
Fact is stranger than Fiction
Last edited by LATECH; 10-09-2012 at 05:39 PM.