I want to make a quick thread to explain my erratic idle issues in the hopes that others who search will find it.

My IAC and decay rate were both within specs. As well as the TPS.

I still had erratic idle when the HVAC was on and occasionally when I'd come to a stop in Drive.

The first thing I did was change my PCV and all the worn vacuum lines I could find. My hard plastic lines were fine but the rubbers were pretty weak. Probably from the previous owner using a corrosive solvent.

Then I recharged my A/C. This helped tremendously. The problem from that point was nearly non existent but I could still tell there was something odd.


Previously I had no normal reason that I could see to check my Alternator. It started like a champ, drove perfect and did not give any symptoms of being bad.

Also the DMM read 13.8V which by my standards 13.8-14.3 is golden.

Ready to close the hood, I decided to turn on the HVAC and Heads.

Boom... 12.5 volts and it would not clime back up.

Changed it out and now it runs like a Swiss clock again.

So there were several little things that helped cure an erratic idle.

130 amp alternator with Life time warranty was $160 at auto-ho.