Bogging/stalling when braking

[thelawdoc]

Gentlemen, I just did a tune-up on my '66 C10 250/2spd PowerGlide/Rochester B carburetor/P&C dizzy. She starts nice. Idles nice. Drives nice. But: when I brake she bogs and stalls. Not intermitently. If I do not brake, she runs just fine at all speeds. As soon as I brake, I get bogging and a stall. I can sort of "get around" the impending bogging/stalling if I give throttle immediately.

I adjusted timing. I adjusted carb idle & mixture. Fuel pump is fine. Plugs new and clean. Wires new. P&C and rotor new. Condenser new. Fuel filters new. No vacuum leaks. Carb just rebuilt. New balancer. Timing gears new.

I have on hand a new coil and a new vac advance which I did not yet install, but I somehow feel that these are not causing my problem. I have a vacuum gauge but did not check vacuum because I have a nice idle and running.

I suppose there are many possibilities/suspects for bogging. This morning I was going to take off the carb and check the needle for dirt. Any other ideas?