06’ turbo ran great for 26k. Then hesitation at slow acceleration between 55-65. Only use high octane with all service done by Subaru. Taken car back four times. They reprogrammed computer, then oxygen sensor, then air filter. Master mechanic admits car has problem yet can’t fix it. Rep says its a fuel issue or polution problem and live with it. Dealer has offered a slight discount on new car and admits that he would send mine to auction and not on used lots. She’s in showroom condition.
Help!
Glad I am not your mechanic. There are so many things that could cause this and few of them are reproducible in the shop unless the car is on rollers.
My first suspect would be that the EGR is opening up too much at that load and speed, or is sucking fresh air. I don’t know if you can disable it to test this theory without setting a computer code which might cause confounding symptoms. See if there is a spot where you can separate the tubing to the EGR and slip in a piece of gasket without a hole in it (i.e. a blind flange) to stop the flow of exhaust gas. See if that makes a difference.