P0446 and trouble getting fuel in tank (slow)

When I bought my car I was never able to put more than one to three gallons in it without the gas pump clicking off. So, when I go to the gas station I am there a long time putting in two gallons, waiting ten seconds and doing it again.

I never thought much of it other than the car was old and it was something I did not care to fix. However, I just moved to a state that tests emissions and I got the code P0446.

I googled that code and noticed that the P0446 codes often coincides with no being able to gas up the car normally (as there is some sort of pressure issue).

Everyone said that replacing the vent solenoid fixed the problem right away so I bought that and installed it on my car fairly easily. I also replaced the canister purge solenoid near the engine for good measure.

I then drove about half a mile to the gas station to be able to finally put in a steady stream of gas. However, I still have the same problem. I was not able to put more than a gallon in my car at a time.

Is there something else I need to check to change? Or is it possible I installed it incorrectly? Got a defective part?