Need help: engine turns off on it's own

I've personally had those nuts come loose before, and man the car will run like shizzola when they do. The nuts can go from loose to gone really quick. I found one when I was working on mine, watched it vibrate right off while holding the throttle open with my hand. Why would the brake guys mess with the carb? No reason to do so. Did they mess with it? The world may never know. If you are suspecting them, then you already have a reason or a feeling that you shouldn't trust them....

Maybe this comment..."
I was told be "mechanics" my timming is off, my fuel pump is bad, and possbile the carb is gunk'd up."

If they know what the issue is, you may not want to take it there again. ( because they caused it )

If they don't know what the issue is, you don't want to take it there again. ( because they are guessing ) How do they KNOW the timing is off? Did they check it while they were working on the brakes?

Something sounds odd about this whole thing.

If it wont stay idling then it's most likely a vac leak or plugged idle circuit like Cudamark said. A loose carb will cause a huge vacuum leak