I've got a couple of problems that may be related, I've thrown a lot of time and nickels at this thing to no end. 94 Dakota, 2.5, 5 speed manual.

The two symptoms are:

Engine does not come back down to normal idle speed quickly, it hangs for a 3-4 seconds after releasing the throttle. It started doing this randomly several weeks ago.

I have a rough idle, I can hear "puffs" from the exhaust pipe at idle which seams to indicate it's a misfire. It idles smoothly after cold starts, and seems to get progressively worse as the engine warms up.

Otherwise the engine seems to run fine.

What I have done:
New injector, rebuilt throttle body, new IAC
New wires, plugs, distributor, ignition coil
Check ignition timing, 12* per FSM
New crank position sensor
New coolant temperature sensor
Checked all vacuum lines, new air filter
Checked for ODB trouble codes, none
New head gasket
New intake gasket
New o2 sensor
Unplugged the computer for 30 minutes in attempt to reset it

All to no avail. What do you guys think?

Thanks

 

I know this thread is old but I'm suffering from he exact same issues. Any help would be appreciated.

 

Hey guys, I did some searching and this is the closest I found to my problem. I just replaced the IAC and that fixed the idle issues but a few days later it started hanging with a high RPM when I shift. Could the new IAC be bad or not calibrated. I tried the unplug the battery and leave the key on for a while. Does anyone have any thoughts?