Well i looked down the throtle body and saw a very thin layer of oil on the bottom of the pan. May be my issue. I also notice that the gasket on my waterpump (replaced 2 years ago) is leaking on the passenger side now. Could this possibly be because of the vibration the engine is making? I dunno, seems like everytime i turnaround there is another problem. Oh well add it to the list...

 

A very thin layer of dried oil is comin because of normal oil vapor.

Gasket is leaking, well fix it!

I'm now thinkin about the vibration dampener?

 

The thin layer of oil is wet, the pan is totaly clean.

 

Personally, I would take it back to the mechanic and let him know what is going on. I don't think it's the intake.

This makes me think that the O2 sensor might be failing and running the truck rich?

 

Not sure, dosen't pull any codes. It is going back into the shop in the morning and I think I will stay and supervise for a while. Ill let you know. Thanks everyone!

 

I'm deffinetly interested in finding out the cause of the low MPGs I'm having the same exact problem with mine right now.

I used to always try to stand around and watch the mechanic work on my vehicle. I say used to because by watching I leanred how to do everything myself now haha.

 

CAT or O2 sensor

 

In my case I got mine both replaced twice, second time both at the same time, still no difference.
In his case that could very well be it, most likely the O2 sensor is acting up.

 

+1 hydra I believe it's an O2 sensor as well. I would think if it was the CAT acting up he'd get problems that aren't RPM specific but hell, you never know.

Definitely start with the upstream O2 sensor and then move to downstream or CAT.

 

A bad or blocked CAT would cause you to loose only your high RPM power also.