I'm using a 96 Dakota frame, drive train and all under an older Dodge truck sheet metal.
I've finally got the chance to drive it a bit. The 318 idles at 1200 rpm in gear (auto trans). Everything is still 96 Dakota, I pulled everything out of a 44,000 mile 4x4 truck with a rusted frame, transferred everything over to a different Dakota 4x4 frame, then added the older sheet metal.
I'm using the Dakota EFI, which I assume is still OBD1. its got the beer barrel intake and port injection. Doing the key thing, I'm not getting any codes. There is currently no exhaust past the rear O2 sensor. Before that back O2, there are no exhaust leaks.

I've checked all the vacuum hoses and they are all good. I've pulled the thing at the back of the throttle body that always carbonizes up, it had a little carbon build up, but not much. I've cleaned the little build up that was there off with carb cleaner, and also sprayed out the cavity (I can't see how clean that is). That made no difference.

I played with these things when they were new, but that was a long time ago. Some direction would be good. Thanks, Gene

96 is OBDII

High idle is either a vacuum leak or something holding the throttle open. I don't recall if they had a mechanical idle set screw or not.

That "thing" is called a IAC (idle air control) it controls the idle. IF all the vac lines are not leaking(this include the PVC valve) it sounds like it's time for a new one. DO NOT get just any brand only get Mopar or Delphi! On a side note make sure the battery is good(load test) and can hold a charge, A weak battery can cause idle issues also.

Pretty sure those are the ones with the vacuum leak caused by the plate under the intake. Scan tool fuel trim numbers might be a clue

Thanks guys, my buddy has a really good scanner for OBDII , but he thought the 96 was still OBD1 as well. I'll have my buddy hook it up on his scanner.

There was a throttle stop under a cap at the top of the throttle that had some adjustment. I was able to drop it back to 1,000 rpm in gear. Its a little better. It also seems to be pretty inconsistent on the rpm, some times its better then others, I'll check the vacuum lines again.. This drive train has been sitting pretty much dormant for about the last year as the truck got built, about the only running its seen was to pull the truck out of the garage and turn it around. Running time may actually improve it, and putting new gas can't hurt either.
I put some new gas in it this morning and ran it out on the highway. The truck runs great on the highway. I did the key thing after the drive (about 10 miles). I'm getting a 12, 45 and 55. There is a dash light on for the air bags, the air bag sensors are on the work bench. I remember the 12 as a recent battery disconnect, and since it was just connected about 2 week ago, I'm pretty sure its no where near the 50 starts it takes to clear that code. I also remember the 55 is the end of sequence. I'm assuming the 45 is air bag related?
Gene

45 is a general fault code for a transmission control issue. You need to get the "P" code that will give you better detail.



This is set at the factory and in most cases should be left alone. The IAC will do the rest.



Plenum gasket, Usually will get multiple miss fire codes and sluggish power if this was the case. But it would be wise to fix it sice it was a major problem with the factory design...

http://www.hughesengines.com/Index/products.php?partid=27091