Turbo overboosting

[WhiteWolf]

I have a problem with my turbo which keeps overboosting. It literally goes off the scale then either cuts out, stutters or comes back to the end of the yellow. Sometimes it doesnt do this..
I checked the resistamcs on the boost solenoid. It was 28ohms. I believe it should be about 30..
Ive checked all pipes for leaks.
With the actuator the boost is incredible and if I time it right by easing off the pedal I can keep boost at 3/4..
Ive unplugged the boost solenoid and it wouldnt go past halfway on the yellow. I assume this is correct as it defaults to a pressure limit.
Im running out of ideas.

I wanted to get it on a rolling road to set it up properly but I need this simple problem solved..

When the car is behaving right it is easy to spin the wheels in third with the slighest bit of moisture..
I was just want it all the time instead of the erratic behaviour..

Any ideas..