I have a 6hp 1987 Evrinrude Yahctwin, Ive only had it about 6weeks and it ran fine always started on first pull, I took it out and motored for about 3 hours with my 25ft Hunter sailboat and it wouldnt start when I got ready to go back. Now it will start when its col after it sits for a few or hours or even a week when it does start you have to keep it throttled up pretty high and it idles very rough. After running it for any amount of time if you throttle it down it will die and will not crank or barely turnover. ?????? I have it on my backporch now not knowing what to do with it. I tried checking the spark by laying the plugs up against the block I couldnt get it to spark tho. The plugs are new. I dont understand why it wil crank if its cold but I cant get it to spark? 