Hi, just wondering if anyone has had a problem with there twinscroll running rough and bogging at low revs? Had a code for o2 sensor bank one so I changed that and the code has gone but now and then the car still does it, it’s fine past 3k revs it’s just low revs, cleaned the maf sensor but I don’t know what else is could be starting to annoy me as it doesn’t always do it. 
any help will be appreciated 

tia

When was the last time the spark plugs/ air filter were changed and was the replacement o2 sensor a genuine Subaru part ?

Try checking for vacuum lines or intake air tract leaks , if you're not sure how to do this yourself.  Ask a garage to do a "smoke test "

As a misfire or air leak, could send unburnt fuel through the exhaust and give a o2 sensor fault .