Truck starts runs for two minutes then dies

I can start the truck. I can drive it for aboUT
two minutes then it dies and won't start
back up for a couple minutes. Its a problem
that has gotten worse and worse. It started
out driving for twenty or thirty mins at a
time and now its progressed to this Over a
course of three weeks. New battery starter
was tested and so was the alternator. Im
not sure what the problem is.