I own a 95 f 450 super duty bucket truck. I recenty put a new transmission in and it ran like a race truck. About 2 weeks ago I noticed I was starting to lose power after it was warmed up. If I started the truck to let it warm up .....no power. If I just jumped in it and went I could drive for about 10 miles....then no power; like I was pulling a 10, 000 lb trailer behind me. I put a new fuel filter on when I replaced the front tank pump about a month ago, the plugs wires cap and rotor have about 7000 miles on them. I thought maybe vacuum leak so I tirec the either under the hood trick and no change in rpms, changed speed sensor, pulled the codes and NOTHING! I noticed the other day I was driving and I switched fuel tanks the spedo bounced and all of a sudden I had power then it died off again, so I switched them back and...spedo bounced and power again for about 20 miles. So I continued this till I got home . jumped in it this morning...no power and the tank switch trick doesnt work anymore either Please help im outa ideas. Thanks