At a loss!!!

I have a 66 mustang coupe, I6 conversion to 302 V-8. It has an Edelbrock 650 cfm 4 bbl, Edelbrock Performer dual plane intake, HEI ignition, Gt40 heads with headers. The transmission is the C-4 auto. The engine runs fine when first started and does so until water temp reaches around 200 deg. Then the engine bogs down whenever I try to accelerate and runs very poorly (generally dying at stops unless I shift into neutral) at idle with or without a/c on. I've changed fuel lines to 3/8 aluminum tubing running them in the V-8 stock location and double checked to avoid all heat sources. I've readjusted the carb jets, and rechecked the timing. But, like I said, it runs perfectly when cold or cool. I'm at a loss to what to do next. HELP????
 
When cold the choke is on and artificially richening your mixture for cold running. You could be running lean when warm so check your mixture when at operating temperature. Usa a vacuum guage and adjust the mixture screws until you get the maximum vacuum.