The 180* thermostat will also richen your mixture up a good bit...

 

I did the T-stat before the headers and it helped my sporadic RPM situation...til I did the headers. Also, to maybe clear up the O2 sensor readings...when the front one jumps in voltage the rear one seems to follow right behind it. And Teach, I believe the code was P420...cat inefficiency.

 

Metal,
The trucks with a 2002 build date have a single cat.

 

well damn...guess I truly am a "redheaded stepchild"

 

Well, I finally got around to trying out the spark plug anti-foul trick...come to find out, that my rear O2 sensor is too fat to fit through the hole I drilled....I'm back to square one...I did find out that the front O2 sensor is the correct thickness to fit through the anti-fouler...Could I possibly put 2 "front" O2 sensors in my truck? or would the ECM go bananas? The connectors are exactly the same so I was tempted to give it a shot but not sure if it would cause any damage.