Hi, I have a 1989 70 hp mercury outboard. Ran great until last 2 times out. At low RPMs it bogs down, if u turn the motor off it takes forever to restart. This last time it won't, not even over night. Turns over just putt,putt and then when put in gear dies. New plugs, using sea foam. Pissing like a 12 year old boy. TCW3 in tank-when gone going to replace with synthetic. No mix in fuel needed. Is there a standard for adjusting mix and idle? Tried to adjust but do you seat and back off 1 1/2 - 2 turns? Some secret? Also at low RPMs it smokes like hell.