My diesel had some "issues" when I got it. A previous owner was a kid who was going to stack it. He had cut the exhaust off behind the cat. converter and put a chip in the computer. When I first got it there was a car with "ask me about Mary Kay" in the back window that got in front of me and kept slowing down. Each time I'd start to pass, she'd speed up. After a couple of miles doing 52 in a 60 zone, I decided to see what the 7.3 could do. It was a damp rainy evening and when I floored it, she sped up but I got past her. That's when I found out about "rolling coal". I have to wonder what that white car looked like after all the diesel soot settled on it. The chip later died and the computer wouldn't talk to other systems until I pulled it. Since then not a lick of trouble.