My '93 Johnson, a motor new to me, runs fine when I get underway and run at high, 4500 - 5000 rpm, but after idling down and putting it into neutral, and then resuming running, once I reach 2600 rpm the motor begins to shake on the transom. Increased throttle only worsens the shaking. The motor sounds fine, isn't misfiring, seems normal but not able to run above 2600 rpm without the shaking. This has happened every time I've had the boat out. The local outboard shop checked out the engine and gave it a clean bill of health with good compression, and no apparent issues. Anyone else have this experience? Thanks
