Fuel back flow problem

I have a 2000 LS V8 with 160k and I have a problem when filling up at the gas station. When i put the nosle in the tank i can hear the gas backflowing and then the pump shuts off, I wind up having to pull it out about half way and wiggle it around with it starting and stopping and backflowing, but no way can I put it all the way in and fill the tank like normal cars. Any idea's on what this issue is? I know there is a ton of jokes in this paragraph I am even laughing typing it but seriously it sucks to take 15 minutes to fill my tank. Thanks

When filling up at the service pump,try locking handle 1/2 instead of full/Fast or try another service station.

The pump your using could be set very sensitive,because of emmissions and
wasted fuel.

MCGIVER

Your Evaporative Emissions Purge solenoid and/or Evap Vent Solenoid may not be functioning properly. You should check the I/M Readiness tests to see if there are any emissions related concerns.

-Rod

I've done the slow flow trick and same thing it takes a little more fuel but eventually backs up regardless of flow size. I got it from a dealer who just puts state inspection stickers on the car with out actually checking any emissions I am sure its the evap or purge, I'll have to check it out. Thanks for pointing me in the right direction.