Since you’ve replaced the turbocharger and the boost controller, we can rule those out. But could the problem be something much simpler?

It’s possible that the plastic trunking that takes the compressed air from the turbocharger to the engine’s intake has split. When that happens, boost pressure is lost, the boost sensor detects the low boost and winds up the turbocharger to compensate and you have an on-paper overboost situation.

Then, once you’re beyond idle, the leak becomes even worse and the computer simply runs out of turbocharger capacity, at which point boost drops away. That’s preventing the engine revving properly and since there’s no sensor to tell the computer that the trunking is split and leaking, there might not be a fault code issued. Lots of black smoke from the exhaust is often (but not always) another clue that this is what’s happening.

It’s very unlikely a workshop would replace a component it fitted two years and 25,000km ago for free. Spare parts and repairs come with warranties, but generally not over that period of time or mileage. In any case, it sounds more like the clutch or flywheel has failed, rather than the master or slave clutch cylinders.

This model Ranger had a dual-mass flywheel designed to make for smoother operation, but the design cold also lead to premature clutch wear. When that happened, difficulty in selecting gears was one of the symptoms. Some owners when faced with this problem, converted their vehicles to a conventional single-mass flywheel to get around the problem in the future.

It’s very likely that the two lights remaining on inside the car are enough to drain the battery over time. The real question is why a couple of random lights would stay on even when the vehicle is locked up overnight. Initial suspicions would involve the car’s body computer which controls many functions, including interior lighting.

An auto electrician is probably your best bet at this stage. But in the meantime, you can perform an electronic reset by disconnecting the car’s battery overnight. Sometimes this is enough to give the body computer a reality check and will return things to normal. But if it has happened once, it can happen again.