I have a 22' Sisu Lobsterboat powered by two 70hp<br />Evinrude outboard motors. The boat was new in 78<br />so I think the engines have to be about that age<br />too. The model numbers are F70ELCIM. The problem I am having is with the port engine. It will run fine for a couple of minutes and then abruptly drop the Revs from lets say 3000 to 2500. After<br />running at partial power for 2-5 minutes, it will recover abruptly, jump back to 3000 Revs only to do the same thing again. I have a mechanic that<br />winterizes the engines but he has not been able to fix this problem. Is it electrical or fuel related? What should I look for (at)? I don't have a comprehensive manual for these engines and only have the Owner's-Operator's Manual for the<br />E70ELCI's. Location of boat, Shelter Island NY. The odometers read about 700 hours. Help please!