89 firebird 5.7L TPI - Hot-start problem...

My 89 runs and idles fine but when all warmed up and running, if I shut it down and try to start 3 seconds later, it just cranks and cranks... I have to wait upwards of 15 minutes for it to re-start, then everything is fine again. Any ideas?... Thanks.

Sounds like a electrical/ignition issue to me.

Not saying that this is your problem, but it might be worth checking into -

11 years ago, I drove a tow truck for a corrupt company (J*ck's Happy Hooker Towing), and the truck I drove was a 1973 Chevy 1-ton dually with a Holmes 480 dual-winch dual-boom sling bed. This truck had a 350 engine in it, with an HEI ignition system. One day as I was out doing my tows (on my day off, which was an oxymoron), I killed the engine as I went up to this person's apartment. I went to start it back up, and it wouldn't start. I waited 5 minutes, and it started. If I let it run, it'd run fine, but then I shut it off again and it wouldn't start. A light whack of the distributor cap with a 4-lb sledgehammer (out of frustration) got it fired right back up. I then drove it home, and it died 4 times on the way. It never made it. The sledgehammer trick got it started back up 3 times.

The problem was the pickup assembly in the distributor. I walked home and grabbed a spare HEI distributor (my old Pontiac 400 dist), robbed it of its pickup coil, drove my car back to where the truck stopped, swapped the coil and then towed my car back home (hey, I could only drive one vehicle at a time).

I am changing the pick-up assembly as soon as I can get to it... I will report back on findings. Any other ideas? Thanks.

Just for the grins of it, and since you're already there, check your base ignition timing out.