When I try to put gas in my 03 MCS the gas pump will stop repeatedly even though I've barely put anything in the tank. If I try to pump the gas in slower or back the nozzle out a little I can hear a whistling sound (probably air inside the tank escaping).

Do I have a fuel venting problem? I'm finding online that a lot of times this is the carbon canister getting saturated and some of the pellets end up clogging the venting line?

Or do I have a tank vent valve failure?

Not sure how to go about diagnosing this. Any ideas?