Ok, this may be a bit lengthy, but I have been searching for hours and can't find anything related.
Important bits in bold.

Back story.
08 X 62k
My last oil change I did myself and got a k&n oil filter. Took it out the next day and decided to do WOT. Started in second at about 3k and put the hammer down. at about 4.5k ish I felt a MASSIVE jerk (I think some tire squeal possibly) and everything was back to normal...this was 3k miles ago.

I did some research and honestly kinda forgot about it as everything was completely fine after that. Over a few months I heard what sounded like a tire out of balance but no car shake (only hearing rain hit the wheel well at unbalanced speeds). I haven't had the back seat in for a few months so I can hear everything back there. Then started hearing a literal creaking sound when at low speeds coming from the back right that matched the my speed and only when on the deceleration side of the drive train.

Not putting anything together so far because Evos make sounds aplenty, I tried to continue on as normal.
I run my car fairly hard for a DD but a only few full pulls a week and no track time or launches.

Today I took it out to work and gave it some gas and felt the car being slow and what I think was a boost leak sound but I have never heard one but it sounded like boost hit, then "leak" then I got acceleration back in the upper RPMs which is where boost leak is most prevalent?!?!?!?. On my way home it seemed to be pulling like normal, no leak and went like stink!
Tonight I got the same one Big jerk and knew something is up.
Hit the freeway and it did it again.
Seems to be in second gear. Third doesn't do it or the rest as far as I can tell.

I run my car fairly hard for a DD but a only a few full pulls a week and no track time or launches.
Sorry for the long post I just want to get everything out. I need to get this narrowed down. My dealership is particularly downy.
I do have a extended warranty tho so I got that going for me which is nice!
As far as I know mods are full turbo xs exhaust and AEM intake.

Anyone have any idea what would cause such a big hiccup while pulling hard in 2nd?

 

Should this be moved to "General"?

 

do a boost leak test and check for loose connectors

 

Boost cut.

 

I have a friends evo 8 doing the same thing and only in 1st and 2nd. It hits just like boost cut but we checked and it isn't. We are going to bigger injectors then after we will boost leak test.
Then retune the car.

 

Took it to the dealer and they I got a over boost code, fuel cut, and wastegate actuator malfunction...Well great. They don't know how to check for boost leaks so I was going to put one together this weekend, could that cause this?

 

It's the cold, and it's boost cut. Can you pull your ROM or have a friend with a Tactrix cable?

Super easy fix.

 

I don't know any one with one, but im sure that I could buy one online if its going to be an easy fix. What would the fix be? Is it all software? He mentioned that he would like to flash it to the latest map from Mitsu because it pulled a code that has something to do with the offset for the MAF sensor being off by 10% causing fuel cut. He also mentioned that I should clean my MAF sensor but based on the cloud I leave behind me, I don't think that's it.

 

It's all in the software. Either the car was previously tuned, or a combo of the cold and your mods on the stock tune is causing the issue. The load threshold needs to be increased in that range. Easy flash fix.