ok, i have a 98 f150, when i put it in 4h, everything is cool when i drive straight but when i go to turn the wheels seem to lock up and skip a little bit. then to top it off, the 4h wont disengage until i turn the truck off. i really need help.

 

driving on a hard surface will make it hop and skip as the tires need some slippage due to the different gear ratio from front to back. don't know about the second problem mine is manual shift. manual or auto hubs? sometimes backing up will allow the hubs to disengage, try backing while you shift to 2H, or you could have a vacuum leak on the diff. if its push button 4wd

 

they are auto hubss but what icant understand is why when i turn, it seems as if the back wheels are locking up? i mean really locking up. to the point where the truck just wont go unless you force it.

 

If your talking about front skip in 4wd on hard surface, it is normal.
The front wheels are locked to the differencial. When the wheels are turned the inner wheel and outer wheel, as referenced to the direction, are trying to rotate at different speeds so they fight for traction and cause the skipping