Original post by: Mario T ,
Since the problem only happens once the truck is warm, I would check around the engine for any loose fittings or hoses that might have expanded and started to leak once they were warm. It would probably be a big leak to keep the engine from starting entirely, so open the hood with the engine running and listen for any hissing or sucking noises. Pay particular attention to the intake manifold. A vacuum leak can wreak major havok on an engine's ability to run. Another possibility is a faulty O2 sensor. It will be plugged into the exhaust on the engine side of the catalytic converter. It's possible that that is reading wrong once it heats up. From the parts you say you've replaced, the only thing left to check is whether or not your fuel line pressure and flow is adequate. It's a pricey thing to replace, so I would get a fuel system testing kit from your local auto parts store and check that your pump is delivering adequate pressure AND flow. (Though a good kit is also expensive. It may be cheaper to just replace the pump) It would also be a good idea to make sure none of the injectors are sticking, though a good dose of a fuel line cleaner can usually remedy that.