[Mark_T]

Before you go replacing parts there is a quick simple check you might want to do to determine the health of your AOS. Pull off you oil filler cap. If you feel considerable vacuum resistance to removing the cap then the problem is most likely the AOS. If there is no vacuum or slight positive pressure then look elsewhere. Also, a failed AOS will generally produce lots of white smoke and it won't just be at start-up.

Having said that, a small puff of blue smoke at start-up is very common and normal with these cars, especially if it has been sitting for a while or was parked on an incline. I wouldn't worry about it unless it starts getting much worse.

Cleaning your throttle body is something you might want to put on your regular maintenance list anyway. Expect to find things a bit dirty/oily in there if it has not been done for a while but, unless you find excessive amounts of oil in there, then this is also normal.