My WRX has 17.5K and about a year ago I noticed that occassionally when making a stop the RPM's jump up to 2500 for 5-10 seconds when the engine is cold or hot. I took the car to the dealership since it is still under warranty and they claimed that I needed to use name brand premium gasoline. I have done this and this still does not correct the occassional high idle. A mechanic suggested that the computer may need an upgrade but the dealer said there were none available. The mechanic also suggested an occassional fuel system cleaner be added to a tank full of gas. Has anyone else experienced this issue?
Yes. You do intact need to run premium, preferably without ethanol. Your car is drive by wire, as is mine, I took my throttle body completely off and cleaned it. You must take it completely off as this works the best.