2000 outback power loss going up long grades and bucking . No back firing.

I've changed ,tb and all idlers,water pump ,thermostat ,fuel pressure reg, plugs and wires, fuel filter, fuel pump, map sensor.

Now I'm going to do ,cat and both sensors, clean and check E.G.R.Valve.,anything else I need to do .149000 miles just bought this car .everyone has pawn it off to someone else but I'm here to stay and I will get this thing fixed lol I'll replace everything a part at a time until it is fixed lol 

Any codes?  How does the muffler look? Once had one where a baffle inside broke free and was impeding  the flow. 

as John suggested, might be some baffle/cat honeycomb has broken loose and occludes the exhaust when going uphill.

If you live somewhere remote, you could disconnect the exhaust and see if that cures the issue. It will be pretty loud!

A friend had such a condition but it was more immediate. Complete loss of power. Cracked the exhaust after the manifold and he was able to chug a lug home to make repairs.

I think he eventually  just removed the cat and vacuumed out the dislodged honeycomb.

Edited November 24, 20187 yr by brus brother

Thanks young men. I'm getting ready to order one on Monday and maybe 2 new o2 sensors.

I'm kind of like that. Then that system will be done under there.

Also just to make sure I'm redoing all my vacuum lines on intake manifold. These are all really hard so I'll get silicone ones from Summit. 

check knock sensor - they can be cracked/bad and often won't throw a code - one of the few sensors that are OK to swap with $10 ebay unit.

inspect the cap and o-ring on the fuel pump assembly, maybe the o-ring is starting to rupture?

 

I know you replaced the fuel pump etc.,but,have you actually measured fuel pressure while it is bucking?

You have classic fuel starvation symptoms.