Hello guys. I just bought a clark with a d155g motor. Unit only runs with choke partially out and when if runs, it revs pretty high, and when you put it in forward or reverse, it almost dies. I put new plugs in it, and it is getting nice blue spark. I am pretty sure it is in fuel system, but am pretty sure parts are obsolete or close to it. Has anyone upgraded the propane system to a impco regulator and carburetor system? Is this the way to go or is it better to just work with what you have. Any advise would be helpful. Thanks