2000 F250 problems

[amc]

I just bought a 2000 F250 4x4 with 6 speed manual 3 weeks ago. The truck has 106000 miles on it. I started having intermittent problems with the truck losing power. It never ran rough or smoked, it was just very slow revving like it wasn't getting enough fuel. Shut the truck down and it ran fine for a week. I have changed the oil and fuel filter. About a week ago the problem started again but this time the truck would randomly go to idle with SES light on. The diesel shop pull a TPS code (not sure of # now). I replaced the pedal assembly with a new OEM part. The truck ran fine for a few miles and is back to doing the same thing. The truck will run like normal after setting all night but only for about 1/2 mile then lack of power and randomly returning to idle when shifting. Sorry for the long post but would appreciate some guidance.