What the hell?
 

Just to start off, I am a carpenter, not a mechanic, but engine work aside, I can usually figure things out, and I'm lost on this one. This doesn't happen all the time, but it's not uncommon and only happens after my 98 explorer xlt is warm and has been driven for 15 or 20 miles, but it's almost like the 4 wheel low is kicking on automatically and when I turn at low speed, the tires kinda lock up. If I'm at a stop sign, at a complete stop, and go into my turn, the tires will actually squeel, like they are not turning. Won't happen at higher speeds, and then when I come to a stop again, there is a loud sound, similar to the 4 low disengaging, but you really feel it in the truck. What the **** is going on? Transfer case? Shift motor? Possible sensor that's bad? Also, the 4 hi and 4 low lights blink times quite often, I've read this as a common issue that doesn't seem to have an answer to, any thoughts? ??