of maf test, unplug it when the cars off, then start it up, if it runs better, the maf is bad.

clogged cat, does it feel gutless when you floor it? sound like a vacuum under the hood? the cel ever flash when floored?

you can also drive it spirited for a bit pull over look to see if the cat is glowing red, you need to do this at night.

or hit the cat with your hand, ( when cold) and listen for it to rattle inside it. if you hear nothing it should be ok.