1987 Mercruiser 3.0 inboard problem
 

Need professional help!!! Hello to all. Took the boat out today for some lake trout fishing here in NY. Air temp was 25F....water was 44. Cranked over and started fine.....and after it warmed up, I threw it into reverse and it conked out immediately. Retried about 10 times shifting into reverse and forward, and finally it caught on and didn't stall. Took the boat out for 2 hours of trolling and it ran perfect. It seems like I had this problem last year....can't remember what I did. It is getting gas to the carb and the fuel filter is fine. Any thoughts on what the problem might be?