That engine does suffer boost issues sometimes due to the actuator seizing,not easy to get but a liberal soaking with penetrative oil and a lever on the actuator rod often gets them going again
And often the cause of boost issues for many turbo cars, especially those that haven't been serviced very well over its lifetime.
My poor old battlebus used to get a sticky wastegate, which was a big problem, because it had sod all power to start with

. Every time I did the oil, I always used to give the wastegate lever a good wiggle for a couple of minutes. I do the same with the EGR levers on the big pussycat, as they can do likewise. On the Jag, the changeover valve that changes between single and twin turbo usage sticks occasionally, though thats a bit of a bugger to get at - can;t reach from top easily, and from underneath means undertray removal.