I recently got a 1996 Mazda 626 on the cheap, and it's got some quirks I'm trying to track down. When you first start it in the morning, the car idles at 2k until it gets to temperature, where it settles down at 800 RPM. It also shifts a bit hard when cold, and the first time it hits 25 mph after a cold start, the revs jump up to 5k before the car shifts and continues forward (the car has to sit for 5 hours or so before it's reproducible) I haven't checked much other than fluid levels so far, to make sure the transmission wasn't running dry or something. I've repaired all my vehicles in the past, but as they've been all motorcycles, I'm not entirely sure where I should start. I'm hoping the high idle is just a vacuum leak somewhere, but I've heard some cars idle high when cold by design, which sounds really odd.