I have a 1983 75HP Evinrude Model # E75TRLCTE. Last week I dewinterized it by putting new plugs, Champion L77JC4 gapped 40, and changing lower unit oil. I then took it out fishing and to run the motor. It ran great out on the bay and I burned thru about 6 gallons of the gas that I had treated with fuel stabilzer back in January. When I came back in the inlet, it started stalling at anything over 5 knots. I have about a 1 mile or so ride at no wake to the marina. When I got to the slip and put it in reverse, it stalled. Started, put in reverse, stalled. 3x. Finally I was able to hook the piling and pull myself into the slip. I ran the motor on the wash rack on muffs and it idled fine. The carbs were cleaned last year. The motor has never liked running between 5-15knots, either trolling speed or wide open, but never stalled in reverse. Any thoughts?