Evo 8 wont pull past 5000 rpm !

Whats up guys,

Just got my evo 8 like a week ago. Car runs fine the only problem is it wont pull after 4500-5000 rpms! It builds boost at 3000 and stops pulling at 5000. I'm running stock Boost.

Not sure what could be causing. My guesses are

1.Boost Leak...maybe
2.Bad MAF Sensor...maybe
3.Misfire...havent checked.

Let me know what you guys think.


Also the whole motor was just rebuilt, brand new valves guides springs, head job, cams.