When do you need to replace the mass air flow sensor in a 89 buick century linited?

My buick is running rough and stalling when stopped or in park.|||When your check engine light comes on, and your ECM throughs a code saying that your MAF is bad.|||Try cleaning it with MAF sensor cleaner first.|||your pronblem is not the mass air flow sensor. its the idle air control valve. http://www.napaonline.com/MasterPages/NO鈥?/a>