Engine starts and stops electrical or fuel?

Last night; driving, engine falls on its face, stops. (Fuel pump changed just this past june, ) when cycling the key to restart you can hear the fuel pump in tank engage, you can hear the fuel relay under hood energize and deenergize, engine will fire for few seconds. WITHOUT cycling key engine will crank but not fire. Battery good, alt output good. Oil pressure good, when I let it sit for an hour(cooled) it fired and ran yet as I put it under load(ran it for 3 minutes) it fell on its face and will not start again, now 12 hours later, still will not start. 2001-4.3, your assistance is appreciated, hoping its something other than another tank drop. (Bedliner). Thank you