i need help i have a 360 in a 77 truck that when i put it in gear in dies and when i come to a stop i dies any please its an auto

vacuum leaks are the most common problem.

More info would be good too. Hoping it's something minor like a vacuum leak. Something as old as '77 could be a whole bunch of different stuff. How are your basics like compression, plug wires, carb, vacuum lines, etc?

we change three carberator and i can not find any vucuum leak

First how and where are you testing for potential vacuum leaks?
Like don't test just at the carb base, check the intake manifold and all vacuum lines too.
Second your problem could be something other than vacuum leakage. Did you check your basics? Spark, Compression, Fuel?
Where's the float level set on the carb/s you tried?

A good check for vacuum leaks is to use a propane torch (unlit) and just let the propane flow around the carb.,vacuum hoses and the intake manifold at the point it butts up against the cylinder heads. It's possible that your vacuum diaphragm in the distributor could leak too.