2015 wrx 2.0l manual transmission while driving the car in everyday situations i have had (3) distinct problems associated with the engine/throttle/idle. 1) ghost blip: when coming to a stop, around 5-15 mph, put it in neutral coast to a stop idle will inexplicably spike from ~700rpm (idle) --> ~1.2-1.5k rpm (for a second or two...like a ghost blipped the throttle). no pressure applied to accelerator. 2) rough idle: while sitting at a stop, in neutral, ~700rpm (idle) --> will dip to ~650-600rpm for a fraction of second & reoccur every 2-4 seconds. feels like someone lightly shaking your seat from left to right. 3) near stall: while sitting at a stop, in neutral, ~700rpm (idle) --> will dip the rpms low enough that the whole car noticeably shakes...similar to the shake you would experience if the engine were actually about to stall. the rpms will fumble around a bit and then hiccup back to normal idle after 4-5 seconds. all three items have been brought to the attention of the local subaru dealer on (2) occasions w/ the reply unable to diagnose problem and/or it is normal.