Hi There, I bought this great machine, Scag 61" with CV22s engine, but ever since I bought it it has had problems. At first, it would run fine and fast , but then it would loose power and backfire. And now I can start it fine, use it for ten or so minutes and then it will die. I start it , but now its hard to start. It will black smoke and I have to keep throttle at middle and play with choke to keep it running. If I do max rpm it will start choking and missing, as if it were getting too much gas. If I fully open choke it will die. I have to keep choke in the middle or so to make it run somewhat OK. It is when I try to engage that it stalls or if I get lucky and it engages, I do not have full power. As if one of the cylinders were not working. Please, if any one has ideas let me know. I work on cars and I am good at it, but I never had to deal with a small engine before. Thanks so much!