It probaly your fuel trims need adjusting.....

what are fuel trims

Its somthing that needs to be tuned via ecu. Relates to partial throttle..

I'm having this same problem.
HKS 272's, stock intake pipe w/K&N, Buschur TBE no cat, buschur fmic LICP, UICP, forge bov, hallman pro mbc. Car was dyno tuned by Buschur. 0-35% throttle is fine. But as the rpm climbs you hit a threshold where you either shift, or ca-thuk ca-thuk ca-thuk... it makes a loud surging noise and stumbles a bit. Go WOT and no problems. Car screams.

I just bought it, and it was modded / tuned previous to my owning it.
I will take a video of it if you guys want, but it sounds like the exact problem the OP was having.

My guess is cams on the stock 8 turbo, possibly coupled with the bov.
It does feel like its spooled trying to go, even at baby throttle above 3-4k rpm.
But I'm new to evo's. My DSM never did this and its almost the same. 272's, TD05 turbo etc. My buddies SRT4 did this exact same thing when we put the GReddy profec B on it. However the 50 trim on now doesn't do it at all. Is it just being spooled because its a small turbo and cams?
Input please.

mass air or blow off valve,the cams should have nothing to do with it....(part throttle)

So its the forge bov? Too bad I don't have the stocker.

MAF is untouched. Pipe is stock. Just a filter.

I had the same problems until I went with a good tune, and changed over to stand alone with speed density.

:Probably the BOV and Tune:

even know your mass air is not touched it could have oil in it or it could be dirty...

it's all about the tune... bov too, but smooth tune means smooth partial throttle

same thing happened to me after i put on the aftermarket dv w/ ic pipes and intake.

put on a stock bov if you dont have one, it helped 1000 times.

try this too if that doesnt help

https://www.evolutionm.net/forums/sh...d.php?t=245601

Yano... I did just that on my DSM... why it didn't dawn on me to do it on the evo... god only knows.
Maybe because I've only had it 5 days.

PS: Does the Hallman pro bleed? (My turbo XS did) I didn't think they were a bleeder?

If I just put my AVCR on I shouldn't have to do it, right?

+1 on the Stock BOV or recirc. the new one don't vent it

BOV is not vented.
Hallman is not a bleeder.

Any other ideas?

Its not abrupt, or rough PT, its NO PT, car will surge and if you hold it there, slow down... and jerk slightly.
Whilst making the CA-THUK noise... repeatedly... then the boost goes away... I refuse to hold it there any longer than a second or two because I don't want to see what's behind door #3.

Its very annoying. I can't roll a gear out without letting up, shifting, or going wot.
Like if someone was inching up beside you and you didn't want to punch it, but wanted to stay ahead of them. (just an ex)
Assuming you are already accelerating, and you want to increase your speed in gear more rapidly, but not wot... I can't. I hit a point where rpm eventually dictates I get the surge and I either stop accelerating, go wot, or shift and start over.

Its f***ing stupid annoying.

make sure the intake pipe is a S bend intake pipe.

I had the same problem. Changed to a MR metal diverter valve and it went away.