Wrx runs rough when up to temp

[Jacobrichy]

Hi everyone, I’ve got a 2006 wrx and recently it has been running very rough when up to temp, but runs great when cold. Both water and oil temps sit at 90 degrees Celsius once warmed up so that seems to be fine. symptoms include loss of power, bad fuel mileage, hesitation mainly in low revs when pressing the accelerator pedal and in higher revs when going into boost it occasionally jerks fairly aggressively and the exhaust note has started to seem alot more throaty. After it’s been running for a while up to a hour occasionally after coming to a stop and taking off from 1st gear it struggles alot to get going like the revs go up then drop repeatability until I get to around 3000rpm then it takes off. Brought to a Subaru specialist and he told me my fuel and boost is all fine no issues there but I have a exhaust leak and he said the rear 02 sensor wasn’t in spec but could just be reporting what it’s seeing. I’ve replaced plugs, fuel pump, fuel filter, air filter, cleaned all sensors. If anyone has any ideas on what could be going on I’d very much appreciate the help, thankyou in advance.

 

[Jacobrichy]

The car also has some mods, after market unequal length headers, cat less up pipe, high flow air filter, Walbro 225, 3 inch turbo back exhaust with a custom tune.

 

[denny69]

fuel injectors?