Can't get gas to go in tank, and it will spit out gas

There's usually a flap on the fill tube below the gas cap. Try to put the pump handle past the flap, and slowly pull the pump handle to fill the tank.

Try adjusting the valve that holds the tank in place, make sure the hose is not kinked when fueling

on every station? try another pump and see.

the decision to stop is on the pump. not your car.

I doubt it.
Usually the problem is a blockage in the fill tube, sometimes the vent for the tank is not working. But there are several components to the EVAP system.
I would check the filler tube first.

problem with the purge canister it's under the car on the rear that is connected to the filling hoses big problem with those cars. i just installed a new tank new hoses but put a second hand purge unit and my 2005 echo is spitting back and hard to fill. good luck

Every gas tank has a vent tube, so when you fill the tank, air can escape, while the fuel is being pumped into the tank. Some vent tubes are metal, some rubber. Yours is either collapsed or plugged up. Look at the fill tube in the firebird and follow it from the gas cap to the tank, there should be a 2nd smaller tube that is your vent tube. Check to see if it's collapsed, pinched, or bent. This is definitely your problem. Check out this web site for pictures of different fill and vent tubes to get an idea of what to look for. Good luck let me know how you make out. Curt
http://www.carparts.com/REPLACEMENT-GAS-TANK-FILLER-NECK/GP_2005706_N__10618.car

there is a vent pipe that runs along side the fill pipe, this allows the air to vent out of the tank as u fill, check it for obstrutions or a kink, u will need to remove it to check this out.

Try checking the vent tube. if you look under the truck it will go from the gas tank filler tube to the top of the gas tank.

I'd have to check your evap system. Any applicable trouble codes?
When you fill-up, the air in the tank has to go somewhere or it will burp back-up the fill pipe and shut off the gas pump. I'm not that familiar with your particular emission system. Just my 2 cents.

The fule tank vent tube is blocked/clogged. It's the little hole next to the filler hose that invites spiders that clog it up. Blow out the tube and it fixes the problem.