Limp mode vRS 135kw

Skoda octavia combi 2.0 vRS 135kw manual gearbox (200.000km)

Hi,

two months ago my car started to act strange. Occasionaly when i switched from 3rd to 4th gear there was no power at 2.000 rpm and then around 2.300-2.400 the power came back. 
I wasn’t woried until one day the car went into the limp mode when i was accelerating and the glow plug light was flashing.

Took the car to my repairman and he found a loose pipe on the turbo.

His computer is showing only one error code, dont really know what is the number (low/overboost) and it’s the same all the time…

But that didn’t fix the problem, so we then proceed to change the EGR valve.
(Before the EGR valve change the limp mode was appearing randomly, didnt even need to accalerate..)

Still the same issue.

Then he found out that the turbo acctutor was failing. After this replacement there was light at the end of the tunnel until the same problem happend again.

So then he reinstalled the computer software.

That change really maked it seem it was all ok again, but the problem is still here but very very rarely.

Mechanic says that the turbo and engine works fine, so there must be some electronic problem.

Forgot to mention that car runs perfectly.  It goes to 4.500rpm no problem and it can easily reach 230km/h. Until the limp mode ofcourse:)
 

So i am asking for some help or advice what could still be wrong 🙂

P.S.

Sorry for my bad language and typing errors.

Gregor