Volvo: Question on volvo

Question
I have a 1998 Volvo s90, base model, and I amhaving a hard time fixing a high idle problem, it idles at 1000-1200 rpm's .. I've replaced the idler sensor, cleaned throttle body etc, severalechanics have gone thru the codes and checked sys, but to no avail. What could be wrong ?

Answer
If the throttle is ajusted properly ,and the micro switch is set ok i would have to go with air leak .It is hard to put into words the ajustment ,and i am sure you can find it on you tube .If that is ok i have seen the intake leak especially at cylinder no1 .. hope this helps .