No matter what I am doing, the GPU usage seems capped at 86%. It is a gtx 260 superclocked from Evga. I've also been having stuttering problems but I'm not sure it's related. Is the usage supposed to stay that low?
It should be fine, your video card could be bottlenecked by your CPU. You need to post your specs before that can be determined.
No game fully stresses your video card to 100% so 86% seems reasonable to me. If you really wanna so your video card pushed as hard as currently possible, then download the FurMark benchmarking program. Do not let FurMark run for a prolonged period of time since maxing out your card means a lot of heat will be generated.
Generally speaking, excessive heat and electronics do not go well together.
Your i7 920 CPU will not bottleneck your GTX 260, so that's not the problem.
I would guess it might be driver related. Try uninstall the drivers in Safe Mode, then re-install when you re-boot and log in to Windows normally. If you still have issues, then try install an older driver.
You may need to test your card on another PC if possible (like a friend's).