I've got 2 problems that may or may not be related.

1. Truck acts like it has some KR going, but no real pattern. Sometimes when it fires up, it runs great. But always when I run hard for a while it feels like it retards. I had a O2 sensor code a while back, but it hasn't reappeared. When I run the HPP3 PowerTuning, I don't have any underpowering issues, but this isn't a viable option b/c it knocks a little in high rpms. Knock sensor, O2?

2. I've got a powertrain shudder at high speeds. It gets worse as I slow down. I serviced the tranny & trans case...Nothing at all. No codes. I'm thinking rear end, but haven't pulled off the diff cover. The way it feels when it slows is making me think I broke some teeth, worse on the one side.

Wondering if anyone's had some experience/suggestions. Thanks.

 

I can't answer number 1, but for number two check your drive shafts and u-joints. A lift puts them at an angle where they wear u-joints faster and bind more often. My jeep did that back when it actually could run over 60 MPH, and it was due to the drive shaft angles, both front and rear.

 

try finding someone close to you that has autotap and see what is going on with problem #1. your o2 sensor might be going out and it just isn't ready to die yet.

 

Here's a link with some good info for testing the O2 sensors:

http://www.autozone.com/servlet/UiBr...3d8004f602.jsp

Knock Sensor:

http://www.autozone.com/servlet/UiBr...3d8004f7b6.jsp

 

Thanks for the help guys. I'll check it out a little more in depth.