Gasket is not very pliable, especially with age. I would suspect with higher intake flow, the amount coming through blown gasket is a smaller percentage of total air flow. Check gasket, cat and O2 as mentioned above.

 

you can't see oil pooling without removing throttle body, unless mechanic has a boroscope. Also are you burning a lot of oil? There is also a vacuum test you can do to diagnose blown plenum gasket. Anyway i would want a little more confirmation before going ahead.

 

++2 ^^ I'd say for starters just looking through the TB isn't proper procedure unless he/you used a scope. A little oil/crap is normal from the pcv. As stated it the other posts o2 & cat. But if the plenum is bad it needs to be replaced 1st. You can test the cat too. You can also unscrew the upstream o2 and see if it runs better. Most would recommend a new pcv from the dealership and as stated denso/ntk o2's. I would suggest replacing the belly/valley pan with an aluminum one. Also suggested reading is the 'end all be all plenum' thread on the main pg of 2nd gen rams..let us know what's up

 

no im not burning a lot of oil at all,thats what makes me think its not the plenum and do you mean unscrew the o2 sensor before i start it because when i first start it its ok then about two minutes in it will start rough idle then last about two to five minutes then its done and runs ok...so just unscrew o2 before i start it to see if it does it???...and can the o2 sensors be bad and my check engine light NOT come on???....like i said just trying to try easy stuff before trying to change that plenum!!!

 

Yes, unscrew the O2 sensor before starting. Zip tie it off to not let it bang around.

 

And just because you are not burning "a lot" of oil, does not mean the gasket is not leaking.