@carvedeye
Since we don't know what is causing your problem, we can't tell you how to fix it. I am doubtful that a new graphics card would help, but we can't be sure.
1.
I asked you a number of questions that may shed some light on what is causing your problem, but you haven't answered them.
2. If your problem affects more than Quake 1 (I don't know since you never answered my question), then it might be a fault with your machine. *IF* that was the case, then you should contact who-ever sold you your machine. But I would suggest you answer my questions before considering that.
3. As an alternative, is there an Amiga club anywhere near you? If someone could see the problem first hand, then maybe they could help.