98 blazer stalls while driving

i have a 98 blazer 4wd 4dr. 4.3 vortec with 150,000miles while driving down the hwy. blazer will stall with no warning all electrical still works when this happens. any ideas? heres a parts list that wre installed within the past year
fuel pump&filter
EGR valve
spark plugs&wires
dist. cap&rotor
3 oxygen sensors upstream&downstream
ign, coil
intake gasket
cat. convertor
dont know what else it could be?!

Is the Service Engine Soon light on? Does it lose spark or fuel pressure? It would be easiest to connect a fuel pressure tester and tape it to the mirror or windshield and watch it when it acts up.