Okay so this is the first time in a lot of years I’ve had to ask for help, but I’m baffled here, whether it’s too many lates nights at the garage and not enough sleep I’m not sure, but here goes...

I have a golf in here at the moment that had a leaky turbo, so it was replaced, was absolutely fine for a few days, was pulling better than the original turbo, then one night it stopped boosting, ran like a 90 bhp, left it for the night but the next morning it was fine, later again that night she done the same thing again, but this time didn’t recover.

Took the intercooler and all the pipes off, sprayed and filled the intercooler with brake cleaner, let it sit for a while, then blew it out, let the egr soak in petrol overnight and cleaned all the pipes, put it all back together and still the same, put the old turbo back in to see if it’d boost, nothing, won’t boost at all on a turbo I know is working.

Vag com is typically showing “charge pressure control - negative deviation” but that’s it, not other faults, other than the air flow position sensor for the ac but that’s irrelevant.

I’m at a major loss as there are no boost leaks... anyone got any advice ? Feel free to point out the obvious too... thanks