2005 2.5 N/A Power issues

[ferret89]

So my sister is having some problems with her 2.5 Auto NA, she tells me it struggles up hills and a general lack of power in the higher rpm range. Up to about 3000 normal, then loses power.
I haven't driven it recently so haven't experienced it myself but she says its started the last few weeks. I had a quick look under the hood, but couldn't see anything obvious.

Any ideas, I'm going to take it to be checked out but I wouldn't mind having a rough idea of some possible causes when I do. I'm thinking a fuel issue maybe?

[Surge]

Was it serviced well?

MAF sensor cleaned, UEC, clean air filter, good fuel (fuel filter as well), perhaps time for new spark plugs?

Tried resetting the ECU?

Though I'm pretty sure the 2.5i doesn't have much power past 3 -4K rpm anyway. maybe she drove a faster car and now hers just feels slower in comparison?

[ferret89]

Update for anyone interested, this is now fixed.

Issue was that all 3 brake lights were out, and apparently this causes the ECU to go into limp home mode and cut power. New bulbs and some fresh fluids and running like brand new now.

Thanks for your suggestions Surge.

[Da4sti3]

wow never heard that, my check engine light came on when my brake light fuse went but that didnt cause any issue with the engine
3-4k rpm is its highest torque point i believe the 2.5i has a flat spot from 2500-3200rpm from my experience with my car