1981 C10 305 stalling when hot

[ksouthards]

Black Beauty, my cherry 1981 C10 Silverado with 305 and Quadrajet 4bbl, 125,000 miles has started experiencing problems.

Truck ran great until electric fuel pump died. Fuel pump, inline filter and carb filter replaced. New fuel line from carb back to pump. Carb kit including gaskets, needle & seat, float, accelerator pump installed.

Truck is not overheating, but it runs for just about 15 minutes every time and then just stops running. You can hear the motor start to slow down while idling. It will also stall in about the same time frame while cruising at highway speed, so not idle related.

Checked for spark last night after it died to rule out ignition coil and/or module. Good spark present. Plan to check out EGR valve and cat converter tonight.

Truck purrs like a kitten while it's running, then just abruptly quits.

Any other suggestions of things to check? I miss my truck!

UPDATE 8/26: EGR valve has been removed from this truck and blocked off at manifold. Truck ran before without it, so don't believe that's the issue. Also entire exhaust system including cat is nearly new, and no rattle heard in catalytic converter.

HELP!