My minivan was acting like it wasn't getting enough gas, shop said they couldn't find anything wrong with it. now it will cut off while im driving down the road....will also cut off when i put it in reverse sometimes?

First, please have it towed to a different shop.
The mechanic you have now should have fixed the second problem under his original guarantee. I doubt he has the skills to diagnose the problem correctly.
Keep in mind I am getting one side of the story without the details. But anytime you have work done and it is not right, never pay for more work on top of the original. At least without a second opinion.
If you want to discuss specific problems I can advise if given the details, such as trouble codes and the components replaced.

Sounds like vapor lock. Leave the cap from the gas lid undone for a little while.

Sounds like either a clogged fuel filter, or a problem with the fuel pump. The filter should be on the drivers side under the cab, and the pump is inside the tank.

SOUNDS LIKE TWO THINGS,1:YOUR FUEL FILTER,2: FUEL PUMP ASSEMBLY I SAY ASSEMBLY BECAUSE THERE IS NO REAL NEED TO NOT CHANGE THE SCREEN ON THE ASSEMBLY,AND LATER FINE OUT IT IS YOUR FUEL PUMP.ALL OF THIS COMES WITH THE ASSEMBLY(.try this in this order)

Could be a failing fuel pump. GM vehicles are notorious for failing fuel pumps, starters, and alternators. Was the car running hot when it stalled? I would bet on the fuel pump on its last leg, and the extra heat may have made it stop.

Sounds like a weak fuel pump.Check your fuel pressure it should be 41-47 psi with key on and engine off if its not within specs replace pump.

The part where you say that sometimes the car acts like it dont want to crank has me thinking your problem might be with the battery terminals. Check and make sure they are clean and tight. This would be where i would start diagnosing this problem from what you described.

check fuel pump or change fuel filter. its not getting enough fuel, change fuel filter, and it should make a big difference.

They need to figure out what you're losing. Is it spark or fuel?

have you noticed if it happens in the morning or while its raining more? let me know