Weird Low Idle

About a month ago i replaced my IAC and TPS sensors on the throttle body in hopes to cure my idle issues. While my bad idle wasnt cured a few weeks later another issue arrose. Whenever i drive the jeep and come to park it (by shifting into PARK) or even shift it into nuetral the idle drops really low and the engine shakes and then it jumps back up at normal speed. This only happens if i put it into PARK or Neutral from another gear (like drive). Something that might be linked is the other day i turned on the AC at a Red signal while in DRIVE and the engine idle rose to 1500 RPM and then dropped, upon arriving and turning off the AC the idle dropped low and then back up. I am thinking the IAC isnt compensating right, what do you guys think ?

pete

BUMP

pete

when was your last tune up?

Jason

What year?

94 xj ,most components i can think of have been replaced as part of my tune up. Plugs, wires, cap and rotor, fuel filter, 02, injectors...

pete

Anyone have any ideas ? Do u guys think this is IAC related- i guess just bc its new doesnt mean its working right ?

pete

bump
pete

it could possibly be the MAP sensor. i recently had idle problems and thought that the MAP sensor was shot. it is easily checked with a volt meter. Its a box shape on the firewall. it is in the middle. make sure the vacuum hose is connected at both ends (follow it). if there is a leak anywhere in this line your idle can jump all over the board.

why does it only happen when i shift into park or nuetral tho ?

pete

Cleaned the old IAC motor and everything is better. This is the second time i get a part from napa and its bad.

Just to let you guys know.

pete