I've developed an idle problem only in closed loop when warm in Park/Neutral. Soon as operating temp is reached or after I've driven, if I stop and put it in park the idle begins to hunt and after 30 seconds or so it stalls. In drive with the brake on it quits hunting. I thought it was the MAP or a vac leak, replaced the MAP and could not find any leaks. Idle problem remained.

So while dinking around trying to trace the problem I unplugged the ignition side of the 3 wire 02 sensor and the damn thing idles like a clock. Takes longer to reach closed loop but it's smooth and doesn't stall.

I am stumped, anyone have any theories?

A bad 02 sensor is definitely one possibility. Did this car come with a 3 wire sensor or did you add that?

You should also make sure you don't have a bad ground on the O2 sensor, if so with the heating wire connected this would give bad readings. One way to test for this is to temporarily connect a ground wire from the O2 sensor body to a good ground on the engine.

Paul T.

I just posted almost the same exact problem as your having ...code 33 at idle?

Are you getting any codes?