My car is an 2005 evo 8, it's had an intermittent misfire problem that I attributed to a bad 02 and fouled plugs, changed those and it got better for a couple weeks, now it's misfiring really badly, like at 60 on the freeway, but it idles perfect, no fluctuation or anything, I checked it with an obII scantool while there's no code for it it but it said my maf g/s was 0 when the vehicle speed was 57 at 18% throttle, is this normal or is maf toast?

 

I doubt the maf has anything to do with a misfire lol
I would check the ignition connections.

And make sure youre using iridium plugs gaped to the right spec

 

The maf tells the ecu how much airflow is coming in to calculate the fuel mixture, can too rich or too lean cause a misfire? Lol...........

 

swap out your maf. there's only a few things that could be wrong.

MAF
plugs
wires
injector
fuel pressure regulator
injector resistor pack

 

When my MAF went bad it also had a check engine light along with it. My gas mileage was absolutely horrible. I was putting gas in it every other day just to get to and from work which was only a 40 mile round trip each day.

 

Usually bad MAF will affect idle too, but it is a possible cause.

 

Anytime I had a maf issue the car would not idle properly..

 

Thanks to those that contributed, I know I've got a couple boost leaks still but it was def the maf, swapped in new one and problem is gone!