Ok here is my problem just the other day my evo started running like the cat was clogged. In third and fourth gear under boost the engine feels way down on power and I can hear a little rattling like detonation almost. The problem is very prevalent in third and fourth gears, I have no problems off boost at any RPM, so today I started looking for problems, checked for an exhaust leak, a boost leak, a burnt plug wire, I was going to check the plugs but I don’t have the proper spark plug socket.

The reason I think there might be a MAF problem is because when I started the car back up to make sure everything was connected properly I dropped a screwdriver onto the air box lid, when that happened the idle stumbled and the car almost stalled. I tried this a few more times varying how hard I tapped the lid and with all but the lightest taps the idle dropped. After searching around for a while I have found that this is usually an indication of a bad MAF.

Does anybody know any other tests to determine if the MAF is bad?

Are there any other possible explanations for my problem?