Hi i have a 1990 V4 120 Evinrude. when the boat is on plane and it reaches 3500 RPM it runs real fast... like it has more gas or something. i did notice that mu Spark Dwell adjustment is broken. the rod is ok, and the part that hooks to the throttle is ok, but mid way on the threads (plastic piece) are broken and there is no cap. with an adjustment handle. could this be the issue or just another issue?