The intake started making a loud sucking noise one day, followed by loss of power, poor gas mileage, etc. One thing I read said clogged cat, so I tried that with no change. Then I read about the plenum issues for about a month before i finally broke it down and checked the plenum. The attached pictures are what I saw.

The plenum’s gasket doesn’t look like it’s got a visible failure, other than the presence of the oil on the plate. The front edge intake gasket and the back edge intake gasket were both failing, the front one was probably completely failed already, just saturated with oil and crumpled on contact with my fingers. And there’s also a gap (3rd picture) between the edge of the intake ports and the body of the intake ports. What do y’all think? Just try the plenum repair and go from there?

 

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

Use only fel pro gaskets.

 

Shorten the bolts (factory screwed up the design), apply thread locker, reassemble with a good quality gasket, and torque to spec. No real need to spend a pile of $, save it for something that is more entertaining.

 

Once you're this far I recommend changing the timing chain and gears. Yes, I'd fix the plenum gasket and see what happens. Get a new Mopar PCV valve and check for broken vacuum lines also. Remove the IAC valve and clean the passage underneath it. You can clean or replace the IAC valve. Mopar or Standard Motor Products not BWD or any of the junk from the big parts chains.