I have a 1997 6.5 S model Turbo. The truck abruptly started running rough and nearly stalled. Barely made it off the road into a lot. I replaced the remotely mounted pmd and the truck started right up, and ran great for about two minutes. Then it surged at idle like it wanted to take off. I have codes 236,238 and 406. It idles fine and runs okay until it has run for about ten minutes then it seems that only the first third of the pedal works. At about 1700 rpm the truck flattens out. No mater how much pedal you put in it doesn't gain any rpm. On a hill, the truck pulls down. I limped it home but it ran between 50 and 60 at 1700 rpm. No smoke, cuts out a little. Any help is appreciated.