6.5 full throttle when starts
 

I bought a 95 6.5 half ton 4x4 about 6 months ago for $1000. Everything ran good until the pmd went out. Replaced it and the truck was back on the road again. Ran for about 2-3 months and pmd went out again mysteriously. Put another one in it and ran fine for about 3 days and then one morning got in it to start it up and it was like I had the pedal to the floor. Never touched the throttle and it just stayed there. It would stay at about 4 grand and not move. Truck has sat for a month now and not a clue on what it might be.

Any advise would be greatly appreciated!!!