I have a 1994 K3500 6.5 TD 4wd 5spd 220k mi. The ip has been changed to mechanical pump, so no pmd. When it warms up the truck runs rough, and stalls, seems to be worse going uphill. I've tried the cold water trick on the ip, it didn't help. Truck starts and runs good when cold. Please help, I just bought this truck and is my first diesel, don't want to give up on them just yet.