Hi everyone - relatively new member but long-time Evo owner...

I have a bone-stock Evo VIII with 115k miles on it. I've owned it since new, and all the miles are mine.

My problem: under a full throttle, it stutters at around 4,000rpm and again at about 6,000. Normal driving seems fine, though after 30 minutes of driving the idle will be a little rough.

It has had all its scheduled maintenance; I've replaced plugs, plug wires, cleaned the K&N filter and replaced the PCV check valve within the last 200 miles (the problem became noticeable about 500 - 1,000 miles ago).

Any help or thoughts would be greatly appreciated!!

Thanks!!

Rich

 

What kind of plugs are you using? What gap on the plugs?
Regap the plugs to .20 try that

 

is it stuttering when it hits a certain boost?

 

I had the same problem a lil while ago. Fresh set of .22 gaped plugs cleared it right up. Also boost leak test it.