99’ LEGO, 30th. 2.2. Auto. 150k. Stock. New factory front o2 (replaced because I had it laying around not because of issue) new knock sensor. New coil, NGK plugs and wires. New fuel filter.
OUT OF NOWHERE—Intermittent- Car bogs, dangerously so, anywhere outside the first and last 1/8 of throttle range. If I have the car mid throttle- BOG. As I let back out and get in that first 1/8 again it will downshift and surge with life.
Rusty filler neck that throws EVaP code and leaks when filling, sometimes.
Never runs bad when CEL illuminated. Never throws CEL when it runs rough.
This is the 3rd Subaru I’ve had with this issue. Solved those with o2 sensors. The other two didn’t have holes in either of the filler necks, but each had EVAP ghosts.
Sounds like a fuel issue to me, but I'm no professional. Check the pump and sock in the tank, check the throttle position sensor, check your air filter, look for disconnected connectors/damaged wiring... Unfortunately there's a few different possibilities.
Edit: just reread about the previous o2 issues. If your gut says o2, check the wiring harnesses. My Impreza had an o2 code, turns out the wires had gotten too close to the axle. I spliced em back together and problem solved.
I know the feeling of wanting to roll your car off a cliff. Hang in there.
If it was me, I'd definitely grab a cheap junkyard TPS and throw it in. Easy to get to and then you can rule it out. I'd also be curious if there are RPM ranges when it absolutely *won't* bog down. If there are then it might point to it only bogging down in closed loop or open loop operation and you can again rule out some sensors. Does resetting the ECU change the behavior as well? Weather? Car warmed up/cold?