I have a 2003 F-150 4.2 2x2 basic no frills work truck. On 2 occasions almost a year apart, in 80-90 temps, I drove for approx. 1 hr. and after stopping in store for a few minutes, the truck would start easily but would chug like its running on only a couple of cylinders w/no trouble codes. After cooling down completely, truck starts and runs fine. My car shop could find nothing but of course it was running fine when they checked it out. Any ideas out there?

 

could be the fuel pump going out, if the starting issues are random ...