I have a 74 115hp Johnson outboard. I had alittle work done on it before the season started. The mechanic said that he adjusted the trottle screw and may need to be adjusted. While running in idle or slow speeds the outboard will sputter and sometimes die. It will start back up put will continue to do the same thing. If I turn the screw in it seems to run to fast(mph). She runs great at higher speeds. I do not care to take it back to the mechanic due to my temper and lack of time. If it is something simple I can and prefer to fix it myself. The engine never did this before. Fuel lines are new and also the tank. Thanks for any help or suggestions.