2010 Suzuki 150 four stroke will not rev

[diesel dick]

I have a suzuki 150 with 390hrs, I was out a tsea running at 5000rpm for about 2 hours then I slowed to trolling speed for one hour, then when throttling up again it refused to go over 3000 rpm and would slowly drop back to 2500rpm with some adjustment you could just 2900rpm, so a very slow run back in, I cleaned the water seperater and the small filter inside the cowling but this made no difference and it will not go over 3000rpm even in neutral on the throttle.
Any ideas on this greatly apprecieated

[99yam40]

monitor fuel pressures to see what is going on, may have clogging filters and screens.

I would be a good idea to see if you have hurt the sealing properties if the cylinders

[diesel dick]

monitor fuel pressures to see what is going on, may have clogging filters and screens.

I would be a good idea to see if you have hurt the sealing properties if the cylinders

How would you check that, and how would have this happened?