Need help with motor vibration

[kylep123]

When i get my 4.3l HO Cobra up to temp and drive it for about 10 minutes and get it up to about 3000 RPMS the engine or outdrive starts shaking the boat like i am hitting some waves and sounds like its sputtering a bit. I changed coil and spark plugs noticed maybe one of my wires had a little corrosion in it wondering if this is related to fuel, spark(misfire), or if there is anything else. Any input would be awesome

 

[kylep123]

Forgot to post Engine model number is 434APRRGD. 4.3l HO GM engine I have now also checked the spark plug wire resistance and they are all fine... I am hoping for a fuel related issue not compression...it did over heat on me the first time i took it out but did a compression test and seemed to be ok at around 160 PSI and starts up and ran fine the last time i took it out ran for about an hour with no issues....going to do another compression test on monday just to make sure both dry and wet. I have heard about a check valve for the fuel that may cause this is there anything else that would cause the engine to vibrate after it warms up like that?