7.1 XL - No start after Warm up and Shut Down

[TexasJack67]

I have a 1994 with twin 7.1 XL GM TBI - Very strange issue. After sitting and cold (like overnight) both engines start up and run fine until I shut them down. After sitting for a while 10/15 minutes, both engines with start, then sputter and die. They crank fine, but then will not start. They seem to be getting fuel, as through mutiple cranks the smell of gas is strong. I let them sit overnight until completely cool. She starts up every time.
I have changed Distributor Caps and rotors (man they were bad!) and the Ignition Modules, but have the same issue - does anyone have any ideas? Fuel is good - no water, checked that too.