W210 E320 CDI developed a weird issue. Car boosts perfectly fine then if left idling for a minute or two (traffic lights for instance) I pull away and there’s no power whatsoever. Turbo noise completely gone as if it’s not working, it’s not in limp mode as it still revs round to redline however extremely laboured when doing so. I cleaned EGR few months ago so had that off to check and it’s spotless, it’s so weird because if I turn car off and back on again I have full boost up until I pull up for a few minutes. Anyone got any ideas?