Hello y'all. I have a 17hp Briggs I/C on a Murry LT that will NOT run right. I've soaked the carb for two days in a brand new bucket of carb cleaner, put in a new kit including the needle valve seat, and today replaced the high speed jet with a new one. No matter what I do, it runs rich and yes the choke is full off. It will ALMOST runs smooth but is just short of and spews out small clouds of black smoke. Another thing is the air mixture screw will not kill it if screwed in completely. This has driven me nuts!!!! What in the H___ am I missing??? Someone suggested pulling the choke on to maybe 45 degrees. My reply was it's already running rich so why would I add choke to an already overly rich condition!!! Oh, and I've replaced the plugs too and the spark is great. ANYONE with ANY idea as to why will be GREATLY APPRECIATED!!!!!!!!!