I had this problem 1992
gmc sierra sle c1500 stepside 5.7 v8 turns out someone put
security system in it up under driver side behind fuse box n while the removed fuse they didn't unhook the wires running thru it when it would get hot n I cut it off it wiykd take 30 min to an hour to crank n I was dead sure it was starter or solenoid but wasn't