2010 Chevrolet Captiva LTZ P0234 and P0299: Turbo Boost Pressure Issues and MAP Sensor Failure

Hi everyone, I own a 2010 Chevrolet Captiva LTZ (turbo diesel) and am experiencing a recurring issue when driving at high speeds. The 'Service Car Soon' warning light activates simultaneously with a sudden loss of engine power. The vehicle enters limp mode, resets after restarting the engine, but the problem returns around 30 mph with the same error codes: P02304 (Turbo/Boost Pressure Too Low) and P0299 (Turbo/Boost Pressure Too High). The car has recently undergone maintenance, so I suspect the warning light may not be accurate. A mechanic previously cleaned the sooty MAP sensor (part number 96440381), but this did not resolve the issue. I've checked all intake and boost lines for visible leaks, and none are present. My question is: could this simply be a faulty MAP sensor, or might it indicate a deeper underlying problem such as turbocharger failure or ECU malfunction? What steps should I take next? Any insights from others with similar experiences would be greatly appreciated. Thanks in advance!