We went to the lake the other day. I backed the boat in the water put it in reverse after starting it and once in the water accidentally hit the throttle to full panicked and put it immediately in drive then I heard big noise coming from the engine and then the boat had no more power it almost felt like it was running on one cylinder. Once I got home I checked both cylinders for compression I had 120 psi on both I checked the lower unit impeller it was in good shape all the gears were engaging forward and reverse no problem no broken teeth the side of the pistons look good I could see them after removing the side plates and when I remove the spark plugs while running the engine one at a time it seem to affect the engine which tells me both of them are firing ok. Now when I turn on the engine and it’s idling it doesn’t sound right and At full throttle is even worse it seems to be stuttering bogging down and there’s almost a mechanical sound coming from inside of the engine which I’m not sure what it is but I can’t help but feel like something is broken. I don’t know what to do as I’ve done everything I think I can to check do you have any suggestions? The engine is in 1967 Evinrude lark 40 hp I would like to keep it if I can fix it but I’m trying not to spend a fortune to do so.