97-90hp yamaha runs good then bogs down

[farside2]

1997 90hp yamaha gets on plane,can run 4k-5k rpm, after about 5 minutes starts loosing power and bogs down to about 1k -2k rpm and go to throttle up just bogs, engine will idle like this no problem. Doesnt stall out. Disconnected main fuel tank and fuel line,
installed new 6 gal tank / new fuel line / new fuel filter / new fuel / new plugs and tried to run again and same problem. no alarms / mix oil in fuel,not oil injected.
checked motor,dont see any leaks or anything abnormal. motor does'nt seem
hot,block is actually just warm. Water pump working. Shut motor off, shut batteries off/on - restarted and idoled for 5 min,throttle to wot and planed off and ran a little longer
before bogging down again. Is it going to safe mode.? was planning to replace fuel pump and water temp sensor. would water temp sensor cause it to do this or should i be looking at electronics.
Any advice would be helpfull. Thanks, Mark

[99yam40]

Test alarm system to see if it is working.
Check timing with timing light while problem shows up to make sure timing is not being retarded.

Monitor fuel pressure and vacuum to see if that maybe a problem

[farside2]

Do i jump out the H2o sensor while motor ignition on or running? Never have heard the alarm go off. Have repair manuals to check timing etc, not sure about the vacuum,will dive into this. Thanks.

[throrope]

Wish you had a solution. Mine's going to the shop tomorrow for the same reason.

[farside2]

hope its something simple, i'm going to replace the fuel pump and temp sensor and give her a try. let me know what they find and i'll do the same..Thanks