Hi all. Tractor is a 1949 frontmount. Been running great except an exhaust leak at the manifold number 4 port. So I changed out the manifold with a new aftermarket. Tractor runs like crap now, soot all over plugs within 30 minutes run time while hogging, noticeable power loss. I clean the plugs it improves and then soot all over again. This tractor until this had zero deposits on plugs, always a nice grey color. I notice one carb nut is a little off kilter and not really tight and it wont tighten anymore. Pull carb and see I had left old gasket on which probably took up some thread space. Carb was on with two gskets. Thought this was causing the sooting. Reinstalled carb with one gasket thinking that would cure it and it did help a little bit but pulled plug and still getting black and sooty again. Does a gasket leak cause sooting? Maybe I'm still leaking, had to use the old gasket again but it wasn't too bad. The idle mix screws although I have messed with them some are about back where they were before my sooting issue but why is it still sooting?