Thought it might be the EGR valve. Took it out and cleaned, which it wasn't really dirty, and checked it with a vacuum pump. Tested good so I put it back on. Thought it could also be the O2 sensors, so, I unhooked all 4 of them and no difference. Probably shouldn't have done that but to late now. Changed fuel filter, no difference. Checked all sensors that I could find and all checked good with an ohm meter according to a Haynes manual. Only thing left is compression and an injector. Injectors look to be a real bi*#h to change. There is a sticker on the door that says the PCM was reprogrammed when the truck was 1 year old. Wonder if this might have something to do with it? I wonder this because the truck will run well over 100 mph. The needle hits the dash where the D for overdrive is. No I don't drive like this all the time! Had to know what kind of a truck I had when I got it. Just never know when you might need a little extra speed ya know.