Bobcat T300 fuel/ power loss

I have a T300 that bogs down way too much when under load, mainly going up a hill. I have replaced the fuel filter, lift pump, cleaned tank. when I take off the fuel filter it is only half full of fuel. It seems to run just fine but when you push the handles forward all the way going up a hill it bogs down to like 1300 RPMs. I have checked everything that I can think of any I still haven't found the problem. Any ideas

Bobcat T300 fuel/ power loss