Lets start with your idle issue. Was it reving up and then cuts out? As the engine slows down it picks up again? Does this sound about right? <br><br>My thoughts. The engine is trying to idle too fast and the idle cut switch (mounted on the thottle body) kicks in and cuts the fuel, the engine cuts out and then as it goes below the preset idle limit switch, the fuel comes back and its starts to idle again. The process continues - up down up down. <br><br>How to fix it. Check all the vacuume lines for a leak. Replace all the small ones just to be safe. Retorqe the intake bolts at the heads too. If the idle smooths out, your done. If not, then you will need to adjust the idle speed. You'll need to disconnect one of the two wires that go to the top switch in the throttle body. The engine should idle fast and not surge up and down. If so, then grab a screw driver and turn the screw on the throttle body until the engine idle is about 850-950 RPMs. Plug the wire back in and it should be fine. <br><br>Now, the rich running condition. (you may have to fix this first before the idle issue) You mentioned that it started to run rich after you replaced the O2 sensor correct? When the engine starts to run poorly and you shut off the engine and restart, does it run good for a few minutes? <br><br>My thoughts... The heavy green wire on the engine wiring harness that goes to the O2 sensor is a co-axial wire. Meaning it has a wire inside a wire. Chances are the inner wire, which the O2 sensor is connected to, is shorting out against the outer wire, which is basically a shield/ ground wire. The inner wire insulation cracks exposeing the inner wire and the outer wire contacts it and shorts the circuit. The computer thinks it running too lean and richens the mixture too much and floods the engine. <br>The fix: Strip back the outer wire exposing fresh inner wire and put a new connector on the inner wire.
