reinstone79

My 2.8L V6 A4 (1996) has 119k miles, and has had alot of maintenance and upgrades lately including timing belt, ABS pump, water pump, all kinds of fun stuff.

When I start the car up, it will idle, and sometimes the rpm will drop to 200 rpm or less almost choking the car out. Even when the car is warm/hot from running, I will come to a stop, in drive, foot on the brake, and sometimes the engine rpm will decrease significantly from 800/900 rpm to 200 rpm or less, and then immediately rev back up to idle speed at be ok.

This is very intermittent and doesn't seem to follow a trend, just does it sporadically, and sometimes not at all. But the car drives fine, accelerates fine, and never has an issue with fuel or missing out or rpm reduction anytime else.

Could this be cold weather related (10-15 deg F outside)? Or is this a sign of a bad fuel pump? Or maybe an O2 sensor? What would cause this drastic drop in rpm at idle, but then right back to idle when it happens? Anyone else have this issue?

I'm baffled...