I have a 2001 F250 with the V10 6.8L. Truck started stalling or studdering on heavy acceleration. Took to the local shop and he replaced the fuel filter. Also checked fuel pressure and it is 40psi. He test drove and said it was fixed. 3 days later and same problem occured, took back and he said it was the O2 sensors and replaced them. Again 2 days later and same problem. Took to a buddy and he pulled the codes. P300 (Random cylinder misfire), P306 (Cylinder 6 misfire), P308 (Cylinder 8 misfire). We replaced all the plugs. Found 2 boots to have a rust coating on them. Cleared the codes and drove for 1 hour at highway speed (80 mph), and it started doing it again. Got out to look for any visible signs and found the exhaust to smell very different than before. Truck has 135,000 miles. Has never had the trans oil changed since I have had it (about 50,000 miles). If you press lightly on the gas peddal it will gain to about 55-60 very slowly. If you romp on it, it spits and spudders. The spitting and spuddering only happens after driving for a 40 miles or so. The truck also does not get as warm as it used to while driving. Wondering if maybe it is the cold weather here in Wyoming.