Truck Trouble:Throttle won't work and engine "pops"
 

Had some truck trouble today...here goes
Truck is a 2008 5.4 4wd Supercrew with 4200 miles on it

I came to work, the truck was a little low on gas.

I had to fill up with gas down the road and sat and worked on a GPS (wireless reciever, unrelated to the truck) unit inside the truck with it idling for at least 30-45 minutes.

Took off down the road and mashed on the throttle and nothing happened. It was still running, but had absolutely nothing for throttle response. It finally decided to work and down the road I went

Made a turn onto a road that had a hill on it at the very first. When the truck loaded up going up the hill it started making a "popping" noise under the hood just like old cars used to sound when they backfired through the carburator.
It was very similar to this sound and was doing it in a similar situation. When the road would level out it would stop doing it. When the throttle was pressed down under a load it would get worse.

The whole time this was going on I never got a check engine light or anything.

I took it to the Ford dealership and they reflashed the computer. They said it was all they could do without a CEL. Picked it up at the dealership. It still had a terrible throttle lag and made the "pop" noise one more time. I'm sure it won't do this when the mechanic gets in it.

Anybody got any ideas?

Stating the obvious - if it was fine before the gas fill up, drain the tank and use another gas station. Rule out bad gas.

x2 its happened to me before. the truck just randomly shut off while going down the highway turned out it was bad gas, good thing i only put a half tank in