yukon shut off while driving

I have a 98 yukon w/ 5.7. Was driving the other day and it killed. Restarted with no problem. Happened again the next day but this time would not start. Upon getting it home to check it out i tested the vehicle wire for the fuel pump with a test light and get nothing from the wires(the key was turned ). Tested all fuses and they are good. So now i'm stuck scratfhing my head. Someone please help.

The fuel pump has a 3 second prime cycle so the test you made would not work, get a fp tester on it, cycle the key a few times and see what pressure you have.

Ok. How is the pump gonna prime if no power is going to it? I did not test the fuel pump but did check the wires from the truck that plug into the top of the pump. If i'm correct the 12v wire should be constant when the ignition is turned, right?

No not till it starts, you have 3 second prime, the engine starts then the pump is powered up full time, check for 12v during the 3 second prime and also see what the pressure is,.

My problem still exists but more baffling. Since my last post vehicle has been running. Although since then i have had ablown head gasket fixed and swapped a bad fuel pump. After getting that fixed truck had been driven for a month and a half with no problem. Started driving my gas saver so truck sat for about three weeks. finally pulled truck back out and drove for a full day with various stops. After my last stop i get in and drive off and 1 mile down the road it kills and won't start again(this is the 3rd time it has done this in the last 4 months). Towed it home and went threw it. Had intermittent spark, had fuel but no start. Changed distributor cap and got it start but won't stay running unless i give it gas for about a minute. Also when i start it revs like i have my foot on the gas. While it is running it has fluctuating idle and popped a p0101 code. Changed mass flow sensor and doing the same. Was told it is the injectors but i think it may be the crank sensor.