Yamaha F150 -04 poor performance

[HydroliftErik]

Having trouble with a 2004 F150.
when accelerating from standing still, it revs up to 4800-4900rpm.
but seconds later it drops down to 3300-3500rpm and the engine starts to shake and vibrate.
When the engine is in neutral gear, it revs to 6000+rpm easily.

i have checked the following:

YDIS, no faults.
Fuelpressure OK.
All fuel filters are new.
Vapor separator OK.
Electric fuelpump OK.
Fuelpumps OK.
Spark OK.
Injectors are cleaned.

it seems to me that the engine isn´t getting the fuel it needs.

Very thankfull for every tip,

Erik

[99yam40]

was any of this checked while problem was happening?

[HydroliftErik]

i have been testing with YDIS while driving, yes.
haven´t checked fuel pressure while driving.

[99yam40]

need to be checking if fuel pressure is holding in spec while problem is there

[rodbolt17]

why would anyone run a test on a motor in the range where it runs well?

YOU MUST test at the RPM and Load the failure occurs.

[Nautical]

Everything checked?? but how about the fuel ?? I would run on a portable tank with fresh fuel, but I think you may have re contaminated your fuel delivery system and have a restriction somewhere ie injectors.