Hello all, I have a 1992 Dodge Dakota LE 4x4 w/ 5.2L V8 that I picked up a few months ago. Noticed poor performance, sometimes very poor acceleration from stop, but no CEL. Checked the codes, said needed O2 Sensor. Replaced it, performance issues largely corrected. But now I have a high idle (~1000-1100, previously 700) and the idle surges, bumping 50-100 rpm every second or so. Tried leaving the battery disconnected overnight, no change. Is it a faulty O2, or what should I check?

 

I suspect you bumped a vacuum line somewhere. There are a bunch on the passenger side of the intake.

 

Also, the faulty O2 may have been hiding a plenum gasket failure.

I'd check for that (quick and simple: With motor OFF, open throttle and peer down into plenum. Is it dirty and oily? If so, most likely the gasket is failing) and consider replacing that.

Also, ALL the vacuum lines are suspect now (What, you expect 28 year old plastic to still be good? Heh.)

RwP