Both rear 02 sensors were bad. They were worse than the front ones and almost seized in there. Took a bit of work to get them out. I have only owned the truck for 40,000 km's so i dont know what other problems someone had with it but I was told it looks like the rears had been changed before. Fired up the truck this morning and the engine sounds like it is running stronger so i hope this fixes the problem. Also did an oil change and put in an additive to help boost the compression. One was down a bit and noticed the truck was using a bit of oil. Cross your fingers everyone that I have no more problems.<img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />