I have a 16 foot center console with a 1997 70 hp evinrude. The motor runs great, but I have problems leveling off. It will level off going really slow like 6 or 8, and pretty well over 25 mph. Between 8-25 ive got to constantly slow down and speed up to try and maintain speed which is aggravating and burns a lot more gas. Anyway is there anything I can do to help reduce or fix this problem, or would I need to replace the throttle if that is the problem?