I have a kohler command 18 CH18S that I just got that rather than a carburetor, it has an impco ca55m-500 lpg mixer on it. I can hook it up to propane and get it to run and idle smoothly, but when I try to apply thottle it gets rough and doesn't seem to be increasing rpm. I have increased propane flow when increasing throttle and still get the same result. I would like to go back to carburated but don't want to buy a pricey kohler carb. Are there any carburetors that would work in place of a kohler carb?