Rough Running JD CT322

Hi guys we have a John Deere CT322 skid steer with 680hrs that randomly runs rough the problem is hit and miss one day it runs great the next it will act up all day. When i say it runs rough it sounds like you started it at the beginning of the week in temps below 32°. This happened once or twice a few months back but it's progressively getting worse. We use the same fuel in all of the equipment so that rules out bad fuel. We changed both fuel filters, cleaned the outer air filter, the inner air filter is spotless, checked the vent on the fuel cap. We are planning on draining the fuel tank this weekend but i was hopeing someone might be able to point me in the right direction. Thanks :Banghead

runs rough how?? smoky, missing, down on power, knocking ??? could be random sticking injector. pump problem. timing issue. need a bit more info to help you.

You say that you checked the vent on the fuel cap. Mine has a vent that comes out of a fitting on the tank. I know because mine stopped up and I had the same problems you are having.