2002 F150 4X4 with automatic tranny and electronic "on the fly". Every once and a while vehicle stops pulling. MPH and tach are working, but vehicle act like its in neutral. Speed was pegged and RPM was about 4,000 as I pressed the pedal, but was coating to a stop. I assume the transmission output shaft is turning sine the speed sensors are located there and am guessing the transfer case is the issue. I have also noticed that the 4 wheel drive light is coming on even with the switch in 2 wheel drive position. Something seems to be initiating 4 wheel drive and I am thinking the transfer case is going into a neutral position is where the issue is coming from. I have to shut the engine off and restart it and so far everything operates normaly until the next haunting episode. The 4 wheel drive does work when I initiate it, but seems to be doing so more slowely than before. Anyone had this issue?

Thanks
Joe