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i have the idle at 850. Now my issue is this. It runs on after i shut it off. It dies after a few seconds. I cant keep the car running with the idle any lower. Manifold vacuum is a steady 10.5.


850 should be low enough to kill it. Either it has a vacuum leak, or you have Alt feedback.
See "My car continues to run after I switch the key off." post.
Does the carb adjust normally? Idle screws kill it @ about a half turn out, smooth idle @ about 1-2 turns out? If not, check for leaks.



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secondly when i try to do a brake stand or apply the gas with my foot on the brake it pops and sputters out of the carb.



This may be the vacuum leak, so fix that first.
If that's not the issue, you need to tune the carb. If it's popping right when you hit it, Accel pump shot and/or squirter. If it hits then bogs, power circuit and/or mains. This isn't the best way to check drivability, either, but I get what you are trying for...