If the revs are going up AND down during warm up,
sounds like the AC compressor is cycling. Are
you starting it with AC on, or defroster blowing?
I also have a 2004 3.0-H6 Outback (35th Anniversary Edition), and I am
experiencing the same rough start problem. In the mornings when I
leave for work, my Outback will sometimes take two tries to get
started, at which point it will run extremely rough for about 30
seconds (sounds like it's running on about 3 or 4 of the 6 cylinders),
with the idle speed going up and down several times, as if it can't
decide if the engine is cold or warm.
Even with all power accessories turned off (air conditioning,
headlights, stereo) the problem still happens. Strangely enough, it
doesn't happen every single morning, but on most mornings it does
happen.
I was thinking about pouring some fuel injector cleaner in the gas
tank and seeing if that remedies the problem. If that doesn't work,
I'll probably video tape a cold startup and then bring the car and
camcorder into the dealer service manager and let him see what is
happening. In my opinion, my new car should be starting on the first
turn of the key, and it should run smoothly afterwards.
If anyone has any other experiences with this, please post. Thanks.