I have an early 99 with 250k miles on it with matt's tunes. I have two problems and I think they are both related to the HPOP. The first problem is when I have the truck set on a higher tune and really open it up, the check engine light will come on and the truck feels like it isn't pulling as hard as it should. I know the 15* hpop is part of the problem, but I also think it is weak. The other problem is not as simple. When I am in stop and go traffic for more than 10 minutes and stop at a light,the check engine light will come on and the truck will idle but not respond to the accelerator pedal. After about 15-25 seconds the check engine light goes off and the truck is back to normal. Could this be related to the hpop, if not what could it be? Any and all help on both issues is appreciated.