Thank you everyone.I do like the K&N filters because I used one in my old Chevy Caprice along with a few other items such as a Hyper-Tech chip, Racing wires, Bosch Platinum +4's, Super coil and a good cap & rotor set. Everything listed is probably why I noticed a difference.
That said I was thinking about changing everything over in my Bronco to try to get as much HP & MPG as I can.
I feel ya on the gas. With the K&N if you've got a buddy with one try it out first. I've used one on a mustang and boy did it make a difference, but the Bronco has such a large filter/airbox that I didn't notice anything. I guess it'll pay for itself eventually anyway, so you really don't lose, but unless you've got a modified exhaust/headers the filter probably isn't where the flow is restricted. I like the filter just for economy purposes, but don't get your hopes up too high on the mileage.
If you do put one in, it would be nice to see a comparison between two clean filters. Comparing it to an old filter is misleading If you can do it, I'd love to see what results you get.
I've heard people getting results from an msd coil, gapping the spark plugs differently, and adjusting the timing, but can't say personally.
Oh, and when was the last time you changed your fuel filter?
brad