Late to the show here but it sounds like your starter bendix might be sticking to me. The bad part is you will have to pull the motor to get to the starter. Not a real hard thing to do but its is what it is. So before you do that make sure all the grounds are clean and tight, check the wires comming out of the key switch for any loose wires, and check the 2 fuses behind the dash also. Good luck and let us know what you find out.......