2018 SHO 250 Stumbles every cold start

[gr8basser]

Hi All, every time I cold start the motor(not being used for 12 hours or more) it fires right up, runs perfect for about 3 seconds, then stumbles and almost dies for a couple seconds while still in neutral, then begins to run smoothly again. It may die if I put it in gear while stumbling. The rest of the day, it starts/runs perfectly. Note is runs great, zero performance issues.

It just started doing this a few months ago before 300 hour service(around 270 hours). Then I hit 300 hours and I went ahead and did the 300 hour service. It actually ran perfect the next couple times out after that, but has since started the exact problem again(my guess is because I primed the fuel system after replacing front engine fuel filter and vapor separator filter). I have tried several things- 1)Prime bulb before startup 2)Turn ignition ON for several minutes before cold start to let fuel pump run more 3)Open fuel cap on boat to remove a possible vapor lock.

My next thoughts are replacing fuel line/primer bulb between engine and Vapor separator filter OR VST Filter???

Looking for some suggestions!

Thanks!