Depending on whether it is a leak or blockage, that P0455 evap code may be the cause of your stalling problem.
The most common causes of that code are:
1. Loose or defective (leaking) gas cap.
2. A leak elsewhere in the system. Such as, the fuel tank grommet, rusted filler neck, loose or defective purge hoses, etc.
3. A defective (sticking) Purge Valve.
I think that you should focus on finding, and repairing, the cause of that code first. It might be causing a vacuum leak of un-metered air. If the stalling problem persists after that is fixed, we can diagnose it further.