HI there

My 2009 3.0TDCI has been losing power over the past few months. It has just come from a service; new clutch replacement and gearbox repair. I noticed the bakkie cuts out at 2500rpm It's really sluggish idles loud and heavy and is really heavy on fuel as if it's just drinking diesel. Engine light came on before I booked it in for the service and repairs.
I tried researching to no success. The intake shutter solenoid valve according the diagnostics is malfunctioned.
Has anyone experienced this issue. I cannot locate the valves as per the below diagram.

Please help


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