I was trying to trace the cause of a noticeable loss of torque around 2000 rpm, and had connected the VNT solenoid pipes together to eliminate control problems. That’s not a good idea though, you get massive over-boost even at 2000 rpm, and strange noises from the turbo; followed by limp mode. I’ve since fitted a boost gauge which is quite good for diagnosing boost problems as you can see the effect of the VNT system working in real time. Mine looks a bit sticky, or possibly just slow to operate. I don’t think that is the cause of the problem, but since it’s intermittent and I can’t be looking at the gauge all the time it’s hard to be sure.