Ok my 1993 Jeep Grand Cherokee Laredo's 5.2L V8 engine likes to surge occasionaly! Usually when I start it up it surges back and forth from 500rpm - 1500rpm, only while in park or neutral. Everything is working properly.

I replaced: O2 sensors, TPS, PCV valve and hose.
I cleaned the trottle body and Flashed the PCM.

I put it on a diagnostic and everything it right, the right voltages, right pressures, everything. Checked every sensor nothing is wrong!!

But it still surges I have No Clue why it is surging any ideas would be great.

My mechanic says that my only other option now is to take it to a Jeep dealer which I am trying to avoid.

If you checked for vacuum leaks and found none check the IAC motor on the back of the throttle body. Might get away with just cleaning it. Also Did you check the fuel pressure when it surges could be a weak pump.

I tried the local corner expert until I noticed that I was being charged $65 an hour for labor. Called the dealership and guess what, they charge $65 an hour. I guess you know where I take my vehicle to now.