150 v max loss of top end

[living the life]

i have a 03 150 v max efi my motor sometimes losses power at top end have only had boat for 4 weeks have 25 tempest only showing 5200 to 5400 rpm but when motor cuts out 5000rpm most it will do from read post i hear about rev limiter mabe o2 sensor not sure what to do first also wondering if i need special tools to take off o2 sensor and do i need a new gasket or can you just put back on with old gasket. want it to be known to original owner of boat never ran boat over 5000 rpm was afraid of hurting motor any feed back would be appreciated

[Hardhead1]

I would have a Compression Test done on the cylinder heads first, then go from there, but what do I know, really not much.

[john tr 21]

change your plugs .

[hooken203]

really sounds like an o2 sensor to me.The previous advise sounds good also pull plugs to check and while they are out check compession. new gasket is needed when o2 is removed. you will need a volt meter and a propane tourch to chech it