im prety sure its related to the knock sensor i  have questions though. as the title says it has no power until around 2500 rpm then like a light switch bam it takes off full power. if i unplug the knock sensor it has normal power at all rpm. i did some experimenting and moved the knock sensor onto the intake manifold and with the sensor mounted on the intake it does not pull power away and i can drive the car normally. i do not hear any knocking occurring with the sensor here. would it be safe to run the car with the sensor mounted to the intake? im 95% sure the sensor is reporting piston slap as the engine does do that. i do not hear any real knocking though beyond the piston slap. it is a 2001 outback with the 2.5 i have a small collection of used oem knock sensors and aftermarket ones they all work normally on a 2001 forester i have and have same issue when installed on the 2001 outback.

Edited January 20Jan 20 by sirtokesalot

well for an update ive been driving it with the sensor on the intake manifold the car has been driving great. still not hearing any knocking by ear. seeing as no one has any input im guessing it must be fine to leave it like this.