Ok so i just did a engine swap swaped out the block and just the bloc, my last one was cracked so i replaced all the bearings and seals. I replaced the tps and Iac several times and just put a new computer in there and still is idling really high at first start up it jumps to 2000rpms then slowly drops to a 1000 when im driving and shift into neutral(manual transmission) it rockets up to 2000 and wont come down i can drive and shift through my gears with out even touching the gas............... when i punch the peddle revs up but doesn't come down as quickly as it should it takes a few seconds. I'm at a lost i checked all my vacuum lines and none of them are broken and all of them are sealed(sprayed some soapy water on them) but i don't think that a vacuum line could cause it to idle that high(2000) i talked to a few people and they suggested a few things leaking fuel injector, cracked intake, and after dealing with auto zone and them being baffled by my situation suggested MAP sensor. I wanted to get all of your opinions about the situation before i go and rip off my intake manifold and check for cracks,i have already unbolted and re-bolted my exhaust and intake manifold several times and really don't want to go at that again please help before i drive it into a tree

 

Is it throwing any codes? Do you have a check engine light on? I'm assuming if you took it to Autozone then they would have tried to pull codes for you...

 

yeah no trouble codes

 

Did your manifold have any cracks in it?

Have you tried adjusting your throttle valve cable?

 

Idle Control Valve, Throttle Position Sensor and/or

is your AC compressor running when its high idling? I remember on another vehicle I owned there was probs with the wiring from the AC causing a high idle.

 

I used a can of brake parts cleaner and found the general area for suspected vacuum leak. Jsut spray it on, the idel will change. THen I put the little red straw on it and focused along the intake/head seam, no change. Fired BPC around the injector seat, idle changed. New O-rings, I'm good there.
Then the MAP sensor vacuum line was giving me grief. It held pressure when I blew into it, but if I wiggled it on the engine, it wasnt sealing well at the sensor. I replaced the hard line with a length of standard rubber line.

 

Slow return to idle when you blip the throttle points toward tps... Did you buy Mopar or parts store?

 

parts store duralast

 

A vacuum leak will also cause high idle, I would make sure all my gaskets and bolts are tight especially around the intake and throttle body. Throttle position sensor only tells the mcu where the throttle is so it knows how much fuel.to.dump. the only thing that makes the motor idle up is an influx of air. I guess you could have an extreme lean condition though that could (I guess) cause high idle.

I have never used brakeleen to do this but,.....I would use carb cleaner or starting fluid to spray the mating surfaces and throttle body base to check for a change in idle.

 

I did too... Failed in two weeks causing slow return to idle. Did a warranty swap and the new one has been good. I can tell you from experience a tps can cause high idle as well.