When I go to fill up the gas tank the gas keeps cutting off at the pump handle and I have to slow the gas pump to a trickle in order to fill the tank.

The problem is that your gas tank "pushes back" like it's full even when it isn't and makes the fuel valve click off. Tom and Ray on Car Talk covered this in a 2007 show and I pasted some of their response below:

"RAY: This condition is probably caused by either a blockage in your gasoline vapor recovery lines or a bad refueling control valve.

TOM: Gasoline vaporizes. How do we know that? Well, when gasoline is spilled, you can smell it, right? What you're smelling is vaporized gasoline.

RAY: And in the old days, when you filled up your tank, all the air inside the tank -- the air filled with gasoline vapors -- came whooshing out through the filler hole or through a vent at the top of the gas tank.

TOM: But then people in places like Los Angeles realized they couldn't see the person standing next to them due to smog. And since gasoline vapors contribute to smog, car makers were forced to install devices to capture those vapors.

RAY: So now each car has a vapor recovery unit that collects the gasoline vapors from the tank and then, the next time the car is started, sends them to the engine, where they're combusted. Your vapor recovery system isn't working, Lottie. One possibility is that one of the rubber hoses is blocked or collapsed."

Try rotating the fill nozzle of the gas hose. thinking to have the open end be in another location of your fill tube..