I inherited a 1979 2.3L Mustang, it has a 2BBL Holley 5200 carb I think. It hadnt run in a couple years... it looks like a lot of failure parts were replaced somewhat recently. So far since I have got it, I replaced the mechanical fuel pump, fuel filter a couple times, new gas, new battery, and new plugs. I took apart the carb and all parts seem to be up to date and rebuilt some years ago. I can start it ok but after about 20 seconds, the idle starts to drop, the engine bucks hard and eventually shuts off. A little white mist comes out the carb and some white misty smoke comes out from under the exhaust manifold. I checked the electric choke and it is getting about 6.23V, so Im not sure whats wrong. Any ideas?