I am no mechanic, so I am looking for advice on what the problem might be. I noticed a few months ago that the tractor started missing while it was idling. This weekend, I was grading a driveway with a pretty heavy grader, and the sound of the engine got very deep, and there was a huge drop in power. I was able to finish the job, but I just bought a heavy duty shredder that I probably won't be able to use until I fix this problem. The sound of the engine is still deeper than before and with far less power. Also when I turn the ignition off, I can hear air coming out of the pistons? kind of like it's exhaling. On a side note, the hydraulic system screams pretty badly. I need to change the fluid, but I didn't know if this would have contributed to the problem. Any thoughts?