1996 dodge 360 magnum. I had engine rebuilt recently. After abit of a fight installing engine. It fires right up and runs great for a few seconds, then starts running rough and dies. If I keep the throttle slightly open it will stay running. Runs alil rough, but will stay running. If I let off the throttle it dies right away. I suspected IAC so replaced it and it made no difference. I checked fuel pressure and it runs right at 50 psi. Even when it dies its still holding 50 psi. Feels like something electrical, but not sure where to start looking. Has new crank senser, temp sensors, map sensor.

 

What brand IAC? Did you clean the IAC well in the throttle body? Kicking any codes?

 

it was uh crap i forgot the brand. Nappa is where i got it. Denso i think. And yeah i scrubbed the throttle body nice and clean. So far no codes.

 

These trucks really only like Mopar sensors in the critical areas. So your IAC still could be part of the problem.

 

Denso *might* be ok....... I would be tempted to plug in with a scanner that can read live data, and see what the assorted sensors have to say for themselves. My guess is, one of them isn't precisely accurate.

 

Did you set the fuel sync?

 

uhh fuel sync?

 

Cam sensor vs. crank sensor. (cam sensor is in the distributor, commonly referred to as "pick-up coil"..... which it isn't.....) The fuel injection is a sequential system, in that it fires the injector for each individual cylinder just before the intake valve starts to open. So, in order to fire the correct injector, computer needs to know where it's at in the firing order. Enter cam and crank sensors. Fuel sync is the relationship between those two. You get about 14 degree window the computer can compensate for, go beyond that, and you start getting some strange performance issues. Since the engine was rebuilt, my guess is your fuel sync is not exactly in sync. Grab the service manual for your truck from here, read the section on distributor R&R. There is a section in there about how to set base fuel sync, which should at least make it driveable to get it somewhere to set it with a scanner.