i have a 2001 5.4L 4x4 F150 7700 "automatic". i hope that this isnt the tranny, but when i accelerate (baby into it) at 40mph-between-55mph the truck starts shaking(almost feels like a big missfire or if the gears are slipping or missing but then feels like they are grabbing again right after "it slips"). but now i just got my tranyy, transfer case , and differential fluid change becasue my mechanic said it might help,and now it seems to be worse that before. now its doing the problem the whole time im driving, i just got my trucks' spark plugs and boots and coils replaced on MAY 4th 2008 too, because i thought i HAD a miss fire. i need ya'lls help more than anything right now, im barely making it by tring to finnish paying off my truck and saving money and i wana goto college but i can't because i keep having to put money into the truck and plus i have to finnish paying off the truck if you have any qestion about my f-150's problem ill be more that happy to give more detail if i can. please help me!!!

 

Check for anything out of balance or loose. Missing weights on wheels or driveshafts. Also check to make sure lug nuts are torqued.