1998 honda 50 idle adjustment

Recently went crabbing and while running the trotline I found my outboard had trouble idling and would stall out when I moved the lever on the remote down. I decided to run the motor up river to see if that would correct the idle issue. After running the motor and then returning to run the trotline the motor would idle but would jerk as though it wanted to stall. That continued for awhile and I again ran up river. After a second run and back to run the trotline the motor started to act right however when placed in gear to run the trotline the idle was to fast. How do I adjust it or slow it down so I can run the trotline at a slower speed. Can the issue be a stuck thermostat