The trigger is mounted under the flyweel inside the stator, the trigger advances or decreases the spark timing to the engine as the throttle is opened or closed at the helm.
Im currently running into the same issue with my 90 sport jet. Except mine will bog down after running it full throttle for 5-10 minutes. It's kindof hard to tell how fast Im going b/c my spedometer doesnt work, but I know Im not going 40 mph like I should be. How do I test the trigger and how much does it cost?