When you said you replaced wiring harness, did that include the one going to the crank sensor? We had a similiar problem with my boys '96 and it was a "break" in the wire going to the crank sensor about 6" from the plug. One other thing you said the fuel pump is OK, did you check to make sure you had power going into the pump at the tank, when my boys pump started to act up it would pop the fuse under the hood, put a new one in (fuse) and it worked good for a while till it hit that bad spot again. ,we changed pump and that fixed that. Kev