It has been a while since the fluid has been changed. I was thinking if I had it flushed, that would solve it. I wanted to check on here and see what you guys may have thought. As for the cat, well I know it is not the problem because when I first bought it in '02, ,the muffler had a small hole and the cat had a small rattle, so being in high school and auto shop I did what any 17 year old would on a 5.2 jeep, I hollowed out the cat and threw a 40 series flowmaster on it. Eventually it was too loud for me and I threw another cat on. I may just end up changing the fluid by dropping the pan one day myself to see if that may help it. It does have 150,000 and I really don't remember ever changing it if I didn't when I first got it.