1990 R3500 454 crew cab dually need help

[BADAZZ86]

I have a 1990 R3500 crew cab dually with a gm crate 454 that has a no start situation when the engine has ran for more than 15mins. I have replaced ignition coil, spark plugs, wires distributor, cap, distributor, rotor and complete distributor and have no idea what to do now if it sits for 20 minutes it’ll restart but if you run it and then shut it off, it will not restart immediately. you have to wait 20-30 minutes. It’s not the starter because it cranks over just fine just does not start. Will start when the engine is cool or cold just fine. Looking for any assistance with this craziness