I have a 03 evo 8 and out of nowhere my car will make boost to 20lbs like it was before (normal) and engine won't get up and go just barely accelerates at all very slow to none pick up need help replaced the fuel pump and still have the same issue.

 

It's kind of a far fetch considering the small amount of details we have on the issue, but a local DSM guy had a very similar issue as you did, when his flex pipe collapsed. Try disconnecting the downpipe and see if you still have the issue.

 

Sounds like you might have a boost leak I would check all the lines

 

If he had a boost leak like that, the car wouldn't hit 20psi...lol


Checked to make sure the cat didn't collapse or clog.

 

You can still hit full boost and have a leak.

 

Could also be OEM rubber intake and/or IC hoses collapsing too.