1998 GT starting problem

So I have a 1998 GT that has been having a hard time starting lately. It will crank for several seconds before almost sputtering to life. I read a suggestion that replacement plugs would help. I replaced those and they did need to be replaced, but the issue persists. So now I am trying to replace the fuel filter but the thing will not disconnect from the fuel line.
I have read several articles on how to change it, and watched a few videos as well. No one else seems to have a stuck one. I am going to try getting a fuel line disconnect tool today to see if that helps, but any advice on wither problem would be appreciated.
If replacing the filter doesn't work, the only other thing I can think of would be the weak battery, but it has never caused starting problems in the past, it just can't stay on without the car being on for more than a few minutes before dying. Again thank you in advance for any help you can give.