I bought a 69 FB that had a 1977 Pontiac 350 installed. Stock down to the EGR valve (that has it vacuum source disconnected) Engine starts and idles fine, runs well. After running down the road a few miles, the engine will not return to idle and dies.

The ERG valve is disconnected from the external vacuum. Could it still be opening by manifold vacuum somehow or do they require an external vacuum to operate? I know these things can get crudded up, but with it disconnected I thought I was safe.

When the car starts cold, it idles fine. It has a hot air tube style choke which opens fully when warm. I can't figure out why it dies after stopping at a red light/stop sign. So weird. This is a 4-speed car. Changed the fuel filter, no vacuum leaks or fuel leaks on the Rochester Quadrajet. Running about 199F.

Any ideas to try? The weird thing is after it cools, it seems to run fine again until its driven far enough to warm it up. After it dies, I can restart it but have to apply considerable throttle to keep it running. Maybe the weights in the HEI are sticking?