2001 2960 Fuel pump issue

Greetings all. 2001 2960 with dual 5.0 GL PEFS Motors. I have a recurring issue where the port side motor will die after anchoring for a few hours. When I’m ready to leave, it starts right up but after a few minutes it will stall out and won’t restart. I thought it might be air getting in the fuel line or the generator feed draining the fuel in the line going to the motor before pulling from the tank but I changed the valve to pull from the starboard fuel tank. I also tried not running the generator when anchored to see if that would stop it from losing fuel. I have replaced the fuel pump several times but it continues to be an issue about every third time I go out. I’ve replaced the fuel pump relays and added a Phenolic Insulator Spacer in between the carb and intake to see if it was vapor lock. Current fuel pump is a month or two old and it happened again today. Any ideas on what else I should try? No fuel in the carb but if if replace the pump it will start and run fine for a few trips but I’m not sure that the fuel pump is the issue.