RPM Jump on one engine Help 99 Speedster SK

[To2d]

I need some help figuring out whats going on here. The Port engine started doing something very odd today where the engine would rev to 4K and sit there for a second or two and then go up to 7K like normal.

Here is how is get it to do it.
Start boat in water
Putt out of no wakezone.
Push both engines to full throttle
*the right engine revs to 7K
*the left engine revs to 4k and then jumps to 7K
When throttling both down after hitting full throttle and pushing back both back to full throttle the left engine goes to 7K no problem.

Also if you cruse at 30MPH and go full throttle it will have that slight delay on the left engine.

All I have done is change the spark plugs and i looked under the boat in the water to see if anything is in the prop. I couldn't see anything and they looked clear.

Looking for ideas on what to look at next or whats going on.

Thanks Guys...

One odd thing i did see was some grease coming from the jet pump Allan fill screw. Both Allan screw are tightly in place. (weird)

 

[To2d]

Update: today when I would give it gas slow the left engine will slowly lose power and stop. It starts back up instantly.

 

[To2d]

Feels like a fuel issue... think i will start with a carb rebuild and new fuel lines. This beast still has the grey lines of death on it.

Anything else I should look to do?