Hey MaxwellD, Alvin Mullen is right on track. Adding compression is likely the place to start, given that you have maxed out volume spacers and psi — if you’re using all of the travel. Generally, the low-speed compression will firm up the shock as it reacts to your body movements on the bike while shifting weight, braking, etc, while high-speed regulates how the shock reacts to larger or harder impacts coming from the ground. The Float X2 is a great shock, and it should be possible to dial it in so it feels right. I would start by adding 2-3 clicks of low-speed compression until it feels as firm as you want it to.
If compression can’t solve the problem you may need a firmer tune. You can send the shock to a certified Fox dealer, let them know the situation, and they will adjust it accordingly. https://www.ridefox.com/content.php?c=foxfactorytune
I hope that helps. Please let us know what ends up working best!