I'm fairly certain that it is starter related. Does the engine crank? Or does the starter not engage? Your starter solenoid is mounted on your starter correct? I'm not a GM guy, but is seems like I've heard over and over where these things get hot and won't restart for awhile. There should be a few GM guys on here that will chime in and let you know for sure. If your timing was real bad off, it would be bad off all the time, not necessarily when just hot, at least I wouldn't think so anyway.