I have an 01 F150 scab with the 4.6L. When I take off under moderate acceleration the truck will shift from 1st to 2nd but before going from 2nd to 3rd (and this is under constant accel.), the rpms will drop slightly and then start to increase again till I hit the shift to 3rd, this happens without moving the gas pedal. Any thoughts? It's been doing it for years but I have never been able to get it to do this weird shift for a Ford tech.