Hello, My name is Robert. I am a Certified Auto Technician with 25+ years experience. I will do my best to assist you. I don't know your automotive experience level, so I may have to ask questions of you before I can answer. I only know as much about your concern as you have stated in your post, so please feel free to add as much detailed information as possible.
If the P0455 code is the only code that you are getting, this will NOT normally cause a stalling problem, The P0455 refers to a "Large Leak Detected" in the Evaporative Emissions system. A loose or bad gas cap can cause a P0455. Likely you have some cracked evap system hoses causing this problem. Inspect all vacuum lines in the engine compartment for cracking, replace any questionable hoses, go underneath and check all hoses on the fuel tank and on the Vapor Canister, same thing, replace any questionable hoses...
It is possible that if the hoses leading to the Purge Solenoid are cracking that it can cause a stalling, as these hoses are ran straigt to manifold vacuum so check these hoses carefully also.
If you need additional information, don't hesitate to ask, I am happy to help until your concern is resolved. Thank you and thanks for using JustAnswer!