I am posting this here in the Dakota section because I have posted it 2 times in the RAM section and no one really seems to know about this problem. Hopefully since the 318 was also used in the Dakota, maybe one of you guys can help.

After the engine gets to operating temperature and you drive it, when you take your foot completely off the gas it stalls. The RPMS drop down to 0 then try to jump back up to operating speed, but that is when it stalls.It threw a code for a MAP sensor 2 weeks ago. I replaced the MAP and TPS. Now it seems to be worse. It stalls everytime I take my foot off the gas. The vacuum lines appear to be ok and I can not find a vacuum leak.

I have also noticed today that the mileage has dropped about 2 MPG and the truck is burning a little more oil than usual. All symptoms now point to the plenum intake gasket, but I'm not sure if this is the true problem.

When I took the throttle body off to replace the map sensor, the inside of the intake manifold was a bronze burnt oil color. I have been told that a little oil in there is normal. Is this normal?

The truck is a 96 1500 with a 318 and auto tranny.

 

I've read similar issues and it was the Plentum Gasket. Especially with that motor.

 

It sounds like the Idle air control motor. They tend to get stuck. Take yours out and clean if you need replace. You may have a vacuum leak too. Get a test gauge and check. I belive the normal is 18 the min. is 15. they are cheep like 10 for a guage.

 

Ya sounds like what my dads old AMC eagle used to do, going down the freeway and let off the gas it would die at 70mph lol what ours was just a leaky intake manifold gasket.

 

I would definetely suspect the intake gaskets. However, the IAC could be a suspect also. I would do both as a matter of course.

 

best thing to do is look down the throtlebody and see if there is any oil. if there is then more then likely its the belly pan gasket. you can also pull the back 2 plugs to see if they are covered in oil. Or pull the pcv valve out and see if when you rev it there is a vaccuum (leaking past the belly pan into the crankcase).

as far as the IAC. yea it is a good idea to clean it out. even if it might not be the root cause... it can still give you a smoother idle once you are done

 

i second the IAC, my 3.9 had a clogged iac and it was doing the same thing, i changed it and that fixed it. my 3.9 also had a bad plenum gasket, although i think i caught it just as it was going bad because there were only two tiny puddles of oil on the pan.

 

I would do the IAC, mine went out last month, the truck wouldnt idle at all. and you can have a light film of oil on the plenum, but any more then that, and its time to replace it.

 

The plenum gasket was replaced about 80k ago. I did the procedure in this tsb

http://dodgeram.info/tsb/2000/09-05-00.htm

to check for leak in plenum gasket and it passed. There was positive pressure in the crank case.

Is the IAC the Idle control arm?

 

IAC = idle air control, also referred to as ISC or idle speed control. It's a solenoid-like dealy in the back of the throttle body. Really easy to replace. Make sure you spray a bunch of carb cleaner down the IAC passage to clean it out.