Try driving another 1999 Subaru and see if it has the same vibration. This should answer your question, as it is not something we have heard of.
Follow-up: I have information that may be helpful to other Subaru owners. I have a 1999 Outback-limited wagon, automatic. I had what "appeared" to be an engine miss about 2800 rpm and in the speed range of 20 -30 mph that occurred on incline while accelerating. In reality, it was a vibration in the drive train. I had the vehicle checked at Wyoming Valley Motors Wilkes Barre PA. The fix was replacement of the front axles; the work was covered under Subaru warranty. This car had 46,000 miles on it and the problem started at about 42000 miles. Please post this info in your column as it may help other frustrated Subaru owners.
Tuesday, October 19th, 2010 AT 1:11 AM