Our 2007 Legacy Station Wagon (owned since january 2012) has recently started to give us intermittent rumbling sound/loss of power for 2-4 seconds only intermittently. It is not loud. On a 15 minute drive it may occur 2-6 times. It feels like maybe transmission/axle/all wheel drive related. (Computer or sensor related ?). Our mechanic, who we have had take excellent care of 9 different extended family vehicles over the last 15 years, is somewhat baffled but has experienced this issue himself on test drives. He just did replace the transmission oil in an attempt to resolve the problem and also looking for bits of metal at that time, but not found no bits of metal and said that the result often indicates that there is probably on transmission issue. We recently experienced a failing transmission on a 1996 Montero and the issue with the Legacy does not feel similar. The local Subaru dealer is a train wreck and dishonest. Our mechanic says he is getting no error codes (don't know if it is possible to check for diagnostic error codes for a long period of time during a test drive). I read one post on another site that seemed to be describing a similar issue and that 5 trips to the Subaru dealer yielded no error codes or resolution but that when the issue worsened, they happened to be near a Firestone dealer who immediately diagnosed a bad sensor, and they replaced the sensor and resolved the issue.
Any ideas ?