400E idle oscillates after shift from D to P
 

Hello,

I have a new situation now.

My car's idle oscillates between 600 rpm to 1300 rpm in a 1 Second cycle right after I shift from D to P, this always happens after I drive the car for half an hour, it has happened twice since last night. If I turn off the engine and start it once again, the idle returns to normal. Before I shift from D to P, I feel I need more brake pressure to stop the car from moving forward. The car is still smooth as silk when driving.

I had wiring harness replaced 2 months ago, where should I start the trouble shooting? BTW, I am running the last tank of gas before oil change, so as usual I added a bottle of Pennzoil fuel system cleaner to the tank, I hope it didn't kill my O2 sensor this time.

Looks like another busy weekend in the garage:( :D

Has the throttle "butterfly" been scrubbed?? & the air bleed hole cleaned out??