Quadrajet about to be tossed.

[TCONNELLY]

I've tried about everything I can think of to get this carb to work right. I had the carb professionally rebuilt by a respected local specialist that has been rebuilding quadrajets for the last 50 years. He replaced the throttle shaft bushings and did a full rebuild. I've also changed to an HEI distributor and new plugs and wires, new ground straps. I've tried every combination of timing and idle mixture adjustment I can think of. The problem is with the idle. It's fine when cold, but as it warms up it starts to stumble and miss. It's very annoying sitting at a light with the engine shuttering erratically. Not so bad that it will stall. It usually runs quite well just off idle and while driving. If I don't give it too rapid accelerator it's quite crisp while driving. The last thing I can think of trying is a fuel pressure regulator. After that I'm out of idea's. If any one can offer any other things to try, it would be greatly appreciated.

Secondarily, are there any Holly's that would be a direct bolt on replacement? Or what would be closest to working. I don't want to get into another tuning nightmare, with changing jets etc.

The engine is a stock 402 BBC, in a 1972 C20.