1996 Ford F-150 Starting Problem

I have a 1996 Ford f-150 truck. It has dual tanks and this problem didnt start til I decided to see if the back tank worked.

This problem only occurs when it is hot out too. It is fine all winter and in the morning.

Whenever I try to start the truck, it is like the negine is starved for fuel. It will chug chug chug and then eventually stall. I have to crank it over numerous times before I can finally get it to run.

I dont know where to start with fixing it. I am pretty sure it is a fuel problem but I am not sure whether it is the pump, or injector.

I read another forum discussing that it could possibly be an electric fuel selector mounted on the left frame being stuck in the "always open in one direction." but I am not sure.

Any help would be appreciated with this.

Thank You soo much