My 3510 skid steer is not running right. It seems to lose power the longer I run it. I first noticed it when it jerked or I raised the bucket. It needed time to catch up. It has got progressively worse. I have changed the plugs and wires, tightened connections, rebuilt the carb, and changed the fuel filter. I do have a leak in exhaust where it attaches to the Exhaust manifold. Any suggestions are welcome