tranny problems wondering about

[LS431o28]

OK! I have a question with 2 possiblities, I think. I'm having problems with the transmission going into drive and reverse and when it is warm it come out of gear and when i give t a little gas to go it slams back into drive. Ive had the transmission flushed and a cleaner and then new fluid added in hopes it would clear the problem up. no such luck. heres part two to the problem. About a month ago I noticed I couldnt shift into 4WD so I took the shifting motor off cleaned the contacts and put it back in place. Then it shifted into 4WD with no problem. Since then the transmission started its temper tantrum but it didnt happen right away, about 3 weeks later. So I decided to check the 4WD again since the tranny problem started and know the 4WD motor shifts in fine but when I disengage it it makes a clicking sound, almost like its trying to go past a point in the shift that it cant, ( not a shift in gears with the tranny but from 4WD to 2WD) but it comes out of gear. and when I shift into drive while in 4WD I get a clicking sound coming from the front 2 wheels when it begins to roll forward also the same in reverse, but it only happens when I shift into drive and reverse. the 4WD drives fine so I am at a loss as to what I should be looking for. I heard at one point since I've owned the truck that a shifting problem could come from a bad regulator in the alternator, has anyone ever heard of that. anyways if anyone can help I'd appreciate it. because I need to take it in By tomorow

Thanks In advance