2 months ago i bought a 2008 f150 fx4 and almost right away had a problem with it wanting to stall and run rough at stop sings so i took it to a local ford dealer and they changed my plugs and replaced a coil, all was well for around 3 weeks and it began shaking and stalling again, it doesnt do it all the time but it does it most often on the way home from work after driving for around 20 minutes in hot weather. i took it back to the dealership and the said its showing no codes and ran fine when they took it out so the told me to take it home and monitor it, it didnt take more then the next day it happened again on the way home from work so i took it back again. this time the mechanic said from the things that are happening it sounds like an engine deather rattle which didnt make me to happy. i had asked them if it could be the mass airflow sensor and they said no because its not showing a code and it would do it all the time. does anyone have any input on what this could be im going nuts.