2011GMC Acadia, when I get gas, my engine dies unless I pump the gas pedal. No problem other times.

Engine off,ignition on, gas pedal to the floor 3 times.

if it goes when giving gas then i'd look at the tps , get the OBD codes read as may just need a reset

The front motor mount and the upper engine strut mount both commonly fail. Start engine and have someone rev engine and let off while you look to see if either mount is moving excessively. The noise you are describing it is likely either or both the mounts.

Not prewired. Will require wiring, relay, and bcm programming for control.

I agree with Peter on this one. Sounds like low fuel pressure. First thing is to be sure that you have around 55-60 psi when you turn the key on and running should be around 55. If the pressure drops much below these no.'s the fuel pump may need to be changed. Don't forget to check and/or change the fuel filter also.

May be the starter or fuel pump. Might not be getting gas after turning it off. the gas may be settling to fast into the fuel pump and none staying in the engine. My friends SUV does not start unless you pump the gas pedal. Not an expert but its what i know it could possibly be.

Carb problems. Sounds like the choke is not working.

I had the same problem and it was the throttle position sensor. have you replaced this? Very easy and solved everything.

if the car is equipt with carburetor,
it must be the automatic choke mechanism.

The fuel pump is located on the frame undrneath the passenger side rear door.If you have the throtle body injection used on the 305 engine the electric fuel pump puts out about 8 psi.
Sounds like you have a clogged fuel pump. Not that bad to change if you have the special tool needed to remove the fuel lines to the pump. Ask your local Auto parts store for help.