I have an 03 F150, 5.4 and it is having trouble shifting from 2nd to 3rd but only when you mash on the throttle. If you feather the throttle you can get it to shift all the way to 4th. I have heard that I need to have Ford reset my shift pattern on my computer or have it scoped to check the TSP settings.
Any ideas?

Chris

 

Could be the accumulator springs, I just went through this, I think from time to time the 1-2 was a problem, but it seemed 2-3 and especially in o/d. Turned out my o/d took a dirt nap on me but alot more things were worn. I ended up getting the whole thing rebuilt and beefed up, works solid now.