My 1974 50 HP Johnson Model 50ESL74M S/N 43775 will not run at idle speed. High speed ok. It appears the problem is in the lower cylinder. I can adjust the low speed jet (even shut it right off) and it makes no differnce. There is oil residue in the exhaust-it burns a lot of gas.<br />I changed the lower ignition coil thinking it was ignition. It made no difference