My 2002 nissan frontier crewcab has been running good then sputtered out then dyed code read 455 evap mass leak took off bed found a gas leak fixed leak it ran great for 20 or so min. now wont start

Not sure when they started it, but back in the mid(maybe early for some models) 2000, large or gross Evap leaks would kill the engine. Only a couple times someone left the fuel cap very loose or off and it kill the engine. Most times it was a broken evap line or the charcoal canister was cracked/broken. Every so often it would be the vent solenoid stuck open. They make kits for the lines now. I would repair charcoal canister. Cranks, silicone and metal/silver tape, holes, a small piece of metal or plastic siliconed over the hole with tape. Clear and recheck codes after driving.

Is it harder than normal to remove the gas cap? If so , it's bad cap. When driving it will create a vacuum pressure in your tank and if that pressure cant be purged then it will not let the fuel move. Now if you remove the gas cap and then put it back on and the car does start replace the gas cap