Plenum is fixed, no change when pulled the 02 sensor to check cat, not sure how old the sensors are. No codes. I haven't done a tune up. Aside from the power loss it runs perfect. I can do the tuneup, figured it was the plenum but turned out to be already done.

 

Try running it with the O2 sensor disconnected. Might just be a bad one.

 

I did today, seemed to be a bit better, not enough to be positive though. I might swap the cat out anyways. I do have 3.55s in there, with the 33s maybe that is the problem. I read this truck can tow like 7k pounds, there is no way my truck would do that.

 

On a 99 the pcv is on passenger side, the breather is on drivers side. Just the opposite on the 01...don't know about 2000 model year. I'm sure chyrsler saved a lot of money on less hose changing them around, Which also means the stock air hat are reversed for the breather hose. I used my stock airbox from my 99 on my 01, just had to use longer piece of hose.

Ijust got an 01 with 77,000 miles and the cat was restricting flow with 5lbs of back pressure. Replacing it helped a lot, especially from downshifting when driving into slight wind or incline. still feels like it's restricted for some reason ,new cat and muffler. The pipes are square shaped where the y goes into the cat.??

That could be your problem if you have pcv going into breather hole on air box, and not into the port next to the brake booster port on the intake.

 

I'll run the PVC into the port just to see. I am going to change the cat out as soon as I can. If it isn't that I will be at a loss, I believe it is a little better with the 02 sensor pulled. Not positive, but enough to make me want to replace it. Weird thing is I have not thrown a code for it yet, I drove it for about 25-30 miles.

The picture I posted with the PVC going into the air cleaner is my exact set up. It is a 99.

 

The pcv no matter what side it's on should go to the intake manifold side port by the brake booster. On my 99 the pcv is on passenger side and the all the 2001's I've seen it's on drivers side valve cover, either way it should go to the port on the intake by the booster hose.