P0102 code Cadillac STS (2000)

Tips anybody?

I've got a p0102 code indicating a ''low frequency'' as GM describes..
So i've replaced the MAF-sensor but no result.... still the same fault.
There are no other obd codes present exept the obvious history codes.

Now what....

I'm going to clean the MAF this evening but doubt that this wil help.
Can i meassure anything at the connector? e.g. voltage, resistance, etc..

UP...up
Anyone?

All has been cleaned an checked now.
Replaced maf, even placed it directly to throttle body tot eliminate leaky tubing between filterhousing/maf/TB. NO result, still low frequency 0102.

But i did notice a metallic rumble in the catalytic converter on idle.
Could a loose monolith inside the cat. be cousing the error?
0102 indicated low air going in but when restricted leaving the exhaust could it cause the 0102??