...and also why you probably had a misfire on #5.

Replace the cat, check your plenum, and probably want to do a tune-up, or at least replace your plugs.

 

Thanks for the great advice guys. Saturday I borrowed a flexible digital inspection camera. I pinned the butterfly open and fed the light into both sides of the intake manifold. Halfway back on the driver side you could clearly see where the gasket had ruptured and was allowing oil into the intake manifold. There was oil pooled in several spots in the bottom of the plenum. I walked inside the house and ordered a Hughes performance plenum kit. I expect to see it before Friday. I will be replacing in on Friday.

Today I paid to have my cat replaced with a Magnaflow unit. I noticed the slugishness decreased slightly, but is still present. I will report back after I replace the lower plenum.

 

Replace the pre cat o2 sensor as well. Do not use Bosch.

 

whats wrong with the bosch ones?

 

many reports of our trucks just not liking them, poor quality, etc.

 

This includes most if not all the sensors on the truck. It seems they operate best with OEM parts. However, NTK is a good brand with good results for the o2.

 

Wouldn't a bad O2 throw up a code?

 

oh i see i just put a bosch one in yesterday so we will see how it goes...

 

Most of the time not until they completely fail. As long as they are sending a recognizable signal, the pcm assumes it's accurate, but a worn or corrupted 02 sensor will often send a bad signal. The PCM, not knowing the difference adjusts fuel and timing curves based on the bad info.

 

Not necessarily. If it's functioning, albeit poorly, it probably wouldn't.