have a 98 outback, 2.5 engine was replaced or rebuilt at 150k. (bad head gasket failure) (This engine was getting 30 mpg on our trip when it starting showing signs of loosing coolant). Anyway, since I can ever remember, even before the engine problems, when it was started and was warming up, it has a vibration that is rythmic. it comes and goes like a pulse, as the engine warms up, i don't notice it anymore. I ask, because; if my engine was replaced, why does it still have this same charactistic vibration? I have replaced some of the usual wear out parts like battery, alternator, starter, radiator, batt cables, plugs/wires, but not a lot of sensors. I just check it a few days ago and got a 1507 code, and seafomed the iac. have not had an idle problem since, and no more engine light, which I saw for the first time. Still has the funky vibration on warm up... My other question? Why does it sound like the squeeky creaky when you hop in, drive real slow, come to a stop and its like the suspension 'settles', with a creak... any ideas anyone? my code reader said every reads ok, (except i had no speedo at the time so it said 0 for it, and the affor mentioned 1507 code) Gots more power and seems to be doing better on mpgs now too...