2008 LCR 320 running rough

[Zbt84]

I have a 2008 Malibu Vride 21' just bought it this season ever since I've had it around 4000rpm it has a stutter I change the  distributor cap  Because it had some  corrosion after that I change the plug wires and plugs for the same reason hoping to clear it up but no luck it seems like it has hickup when under load every once in a while also I've ran several tanks of 93 octane gas through it and use fuel additive every couple of tanks (sea foam ) the boat has 474 hrs on it I've put 125 hrs on it this season joy riding and surfing I check for knock sensors and they are not there just brass plugs and also checked crank sensor connection because it threw a code for it one time and went away after revving in neutral to see if the issue was only under load or not  any help will be  appreciated 

[malibu2004]

Fuel Filter