So my bonnie keeps throwing the gas cap code. I've replaced the gas cap, but that has not fixed it. Everything else, vacuum lines, ect are good. After looking though here, I found a couple posts that said the check the filler neck where the gas cap sits. I checked it, it is pretty rusty, and coming apart. Would I need to replace the entire filler neck? Also, where would I get one?

i can think of any other way to get that to seal besides replacing it. i did my mil'* 96 bonny last year and just went down to carquest they had one in stock for around 110-120.

usually they rot from the other side down, ive never seen one like that even on much older vehicles.

I had this problem and I stuck a rag in the filler hole and lightly sanded at the same time I held a shop vac hose to pick up the standing dust then I wiped it down and put some o ring lube on the opening and the seal on the gas cap. Works good for about a yr then have to re-apply.

Look at the picture he posted of the filler neck. No amount of sanding will correct that. It amazes me that a 2003 can be corroded to that extent, particularly since that is not a common issue for our cars.

Oops I looked at that pick again that and wow I did not see it good the first time with his finger under the metal. Yea not good.

Looks like a good place to try some JB Weld or Steel Putty. Clean the area as best you can, mix it up, press it in, final shape it once it hardens. Should buy you some time.