hello i got a 1966 johnson 5hp motor. starts fine sets and idles fine when i give it full throttle it cuts out for a while then opens up and runs good. i replaced both spark plugs and still the samething. so now i am soaking carb in gas maybe stopped up? also taking flywheel off and checking points to see if they are set right. one more question i have on the front of the cover there is a knob that goes to carb, is that a fuel mixture knob or idle adjustment knob. would like to get a copy of a service manual or something to help me work on this unit