My tractor loses power almost to the point of stalling if I go above creep speed. Additionally, when I engage the PTO, it stalls the tractor. I thought they were two separate problems and I ended up pulling my PTO clutch pump assembly, testing the solenoid, and blowing air through the port while the valve was open. I also changed my fuel filter. When I put everything back together, power resumed and the PTO engaged (although I did not test it under load). Everything worked well for 3 days and the symptoms returned. The only thing I can think of doing is changing the hydraulic filters. Any suggestions? Thanks!