My truck starts fine, but after it warms up, after 5 minutes, it loses power.

I would verify fuel pressure using a fuel pressure gauge taped to the wind screen and see if fuel pressure is dropping off (fuel pressure should be 33 to 37 psi at idle 38 to 44 psi at wide open throttle). When it does loose power remove the fuel pressure cap see if there is a vacuum being created in the tank. Perhaps the exhaust is getting restricted you would need to verify back pressure. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online