howdy;

1987 Subaru GL FI 1.8 SOCH;

 

when running and driving around in town was great---

but when more than 3,000-4,000RPM with half throttle. pretty slipper but when full throttle became smoothly when up the any hill.

 

fuel filter or fuel injection poor? or what?

Id say start by inspecting the easy stuff do a good visual inspection and make sure nothing is out of place or messed up..  Spark plugs, Dristributor cap and rotor, making sure they are not all worn. Throttle body clean, air filter free of blockage.. basic tune up stuff and if you have  the check engine light on check for codes. just some ides for ya. good luck.

i had this problem too, when i would step on the pedal more than half-full, it would bog down but only when i was in the 3,500rpm-6,000 range, i tried everything from the injector to the fuel pump to the regulators to fuel filter, turned out it was my catalytic converter, i gutted it (2cats) and wala, i got like 30 more hp and dont have to let go of the throttle just to make it past 3,500rpm, i have full range of my pedal and rpms now. hope this helps. if thats even the problem. and check your state laws if your going to gut it, in Texas if a vehicle is over 25years old, its exempt from emissions.

Edited April 7, 201510 yr by Subasaurus