When you replaced the rear, did you replace it with a vac controlled rear mount or a solid....I ask as some places offer both for the auto.

Anyway back to the idle. Strange you are getting different readings in P and D, the spec's I have say that it should be ~750 rpm's. I'd look into cleaning the IACV and give the tb a good cleaning as well. Then you might have to adjust the base idle.

When doing all the work, did you give it a tune up as well (cap, rotor, wires, plugs, ect)?

EDIT: Forgot, on the 4th gens there is the air boost valve as well, drivers side of the tb....early, need more coffee

 

I remember it being a vac controlled one.

When I replaced tps I cleaned throttle body, and when I was cleaning egr I said screw it and cleaned the whole intake. And yes I did th entire tune up wires plug cap etc. and I just set base idle when I was doing the tps.

Their is something that might do it, I did put in a aftermarket ect sensor. After I learned after market sensors and gaskets don't work. Had to learn the hard way.

 

Please check the IACV and boost valve. Under load it should help in keeping the idle steady. P or D, you should have the same idle RPM's (~750). So you might need to reset the base idle again.

 

Well I unplugged the booster valve and it did nothing at all, did not raise or lower idle, later I unplugged IACV and the car did not change idle at all, and then when I plugged it back in idle shot up to 1200ish. I reset ecu and now I'm back to square one. Also my idle screw is all the way down, I can't adjust it to go any lower.

 

Check for vac leaks (intake gasket, vac hoses, PCV hose, ect).