Truck not running properly

[72jenny]

I have been working on trying to get my truck running but have ran into some trouble. It has a 350 engine that is .40 over and I believe it has a mild cam. Edelbrock 1406 carb and edelbrock intake manifold. The problem I am having is when I start my truck it runs fine. However, once I am in gear I have trouble. I can usually drive a little ways but then when I get off the gas it will stall. Not sure whether it is the carb adjustments or timing that is off. After adjusting the carb some nothing has seemed to help which makes me think the timing is off. Anyone know where I should be setting my total timing at? Thanks!