Have a small motor problem, or I hope its small. The motor is a 97 tracker 40 horse ( merc )? Anyways the thing seems real hard to start every once in while. After it starts (when in neutral) when you put it in gear it stalls. rWhen the motor runs its great, but it is getting harder to start and get in to gear. The plugs are new, but are a bit dirty. When you clean them it helps. What can I do? Tune-up, carb, any help would be great. thanks.