The car
2000 a6 2.7t, 6 spd man, saloon

Problem:
I left the house yesterday morn on usual 35 mile drive to work, got into town to bank shut the car off, in was in bank maybe 10 min, came back out turn key car cranks but won't start. I waited maybe 15 min starts fine. Drove another 10 min, left it idling while in pizza place for 5 min come back out car is off and won't restart again, wait 30 min for friend with trailer, start it up and drive it on trailer. Take it to my shop 30 min away start it and back it off trailer. That being said, last labor day weekend I had the same problem, it was the fuel pump that time. It just died in the driveway after getting home from work that time. This time I figured it was the pump again, so today I replaced it with a warranty one, ( ps I work at an autoparts store so it makes it easier.) got warranty pump in fires right up no prob. I drive it almost back to the house, it dies as I pull. Up to a stop sign, I towed it to house 3 miles away.

What I have tried so far
( no check engine light on)
I hot wired the pump directly to the battery. I hear the pump run, but still no start, I tried switching pump wires in case I had it backwards, nothing. When I left my shop I filled it with gas, kinda weird cause I know it is an 18 gallon tank but, it said I had half and I could only get 5 gal out to change pump, and got 9 + the original 5 in to fill it.

I am at a loss as to what it could be, gauge says full, all gauges read normal except oil temp which has not worked since I bought the car a year and a half ago.

Any one have this prob please help

Matt