We have a 2005 Equinox and i'm not sure if the way it is starting is normal. When it first starts, it goes directly to its normal idleing rpms of around 900. But then goes down to around 400, sounds like it wants to stall, then goes back to 900 and stays. This happens every time we start the engine but it only stays at the 400 mark for about 1-2 seconds. Not sure if this is typical or not? Thanks!