Check that your MAF is clean. No filter oil on any of the elements.
With the MAF disconnected, the PCM goes into Failure Mode operation and estimates air mass and intake air temp values. So for some reason your MAF is sending a wacky air mass value to the PCM. Just switching between two types of filters shouldn't cause this behavior.
Rob Weiss
'99 Mystique, 2.5L, MTX,Black/Tan, 37K miles
SVT Air Intake & Throttle Hang Plug
Build Date: December 14, 1998
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