I know there's a way to tell, but how do you do it again? what would the symtoms be? thanks.

a service engine light with a code 33 is a dead give away. that and the car runs like crap and then will smooth out if you unplug the MAF while the car is running.

There are several methods of testing a MAF sensor output. The best is by using an oscilloscope on a scrolling raster and watching for sharp drops or rises in the output signal.

If you don't have a scope, you can do the "tap test". With the engine idling and fully warmed, tap on the outer MAF housing. If the idle stumbles or runs away, you may have a poor connection or broken hot wire sensing element. Usually, not always, you'll generate an error code with this test on a failing MAF. Make certain the MIL lamp is working, of course.

Performa an archive search on the topic. There are a couple of other good indicators, including the ECM / MIL lamp as described by "Our Sofa King". Codes 33, 34, and 36 are MAF problems. The ECm reacts to lost MAF signals rather quickly. If the signal is out of range for more than 600mS (6/10ths of a second) the ECM will set an error code.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader