Dead Spot from Air/Fuel mixture? Need Help Please

[99m6t/a]

okay heres how it is my car has a dead spot in it at around 3,000 rpms it happens all the time not just sometimes. It also may occur at different rpms sometimes lower sometimes higher.

Well me and my dad went to a dealer and told them we thought it was the cats to get it checked. The cats are 8yrs/80000 so it got checked for free.

They told us it was a bad air/fuel mixture causing this. They however didn't tell us rich or lean or anything more than it was the wrong a/f mixture.

What can cause this problem or can it be something other than a/f mixture.

B.T.W-- The car has fresh plugs and wires so I highly doubt thats it.

[SeVeReDiStOrTiOn]

Clean the maf with a non-residue electrical cleaner and see if that helps....you could also do a few runs on a dyno with a/f and see if it's rich/lean