Just inherited a Lowe 170 w/ '89(I think) Evinrude 70hp. The last 3-4 yrs. it was only run a couple of times a year. Dad thinks the last tank had a 25:1 oil mix (VRO was taken off) and about 2 gallons of that mix run in it. Have put fresh 50:1 mix in and it runs better but idles low RPM and...