Yamaha 150 running sluggish

[GEH6198]

Bear with me everyone, as this is my 1st boat and Im not too savy with some proper terms. Lol
I've had my 05 yamaha 150 on my 19ft skeeter for roughly 2 years. Had no real engine problems until about this past March when the impeller came apart and subsequently caused the water pump to burn up. After having both replaced the dealer informed me that the harmonic balancer was about to go out and needed replacing as well. I agreed to have this replaced in addition to having a total fluid and filter change. I got the boat back and now i feel like the performance is very lacking to what it should be. With the throttle pegged out i can maybe get up to 38mph with only 2 people apart from myself aboard. If pulling a tube the engine has even more trouble getting above 20mph. Are my expectatations from this motor higher than what they should be or should I be seeing more performance than this?
Update: Went out today and when pegging the throttle down at 30mph i could get up to roughly 44/45mph but it would immediately drop down to 33/34 after about 2 seconds.

 

[99yam40]

might help if you give info on RPM and what it was doing before the shop worked on it

 

[GEH6198]

I dont remember the exact RPM's but they were consistent (i.e. they didnt drop with the speed but rather stayed the same). I wanna say it was around 3800 rpm's at full throttle.
The issue i had prior to taking it in was the water pump and impeller going out. Before that happened i had no mechanical or performance issues.

 

[99yam40]

so you have no idea what the RPMs were at wot before the overheat
and no idea of what they are now?

I would be monitoring fuel pressures to see if it is running low on fuel in the VST

 

[GEH6198]

Yeah, cant say what they were prior. I know today they were around 4000 rpm's.