I have a 89 Evinrude xp150. It runs great for about 29 min or till I hit a wake. Then it drops from 4500 rpm to about 3200. I have ohmed the stator timer base. Changed plugs coils fuel lines fuel pumps plug wire and coils. The wired thing is when it drops power if you turn left it picks up. I have had some one else drive while I pull the cables and fuel lines. No change. Everything ohms out like it should. Also I check the plug wires with a timing light the right bank all hit great but the left bank is sporadic.