i have an 04 tsx with no mods and my rpms drop real fast when ever i rev it. It also constantly idles weird and it feels like it wants to die. I was thinking mass air flow sensor or clogged filter? not to sure...

 

Is Check Engine Light On?

If not, this reduces possibility of a faulty sensor sicne ECU can detect out-of-range input from sensor. It may be possible to get info that does not cause CEL and still causes drivability problems. An engine scan may be necessary to detect fault in this case.

Certainly, a new air filter wouldn't hurt anything, however you should be able to inspect and replace if necessary.

good luck