I’ve got a 2016 fiesta st feeling down on power and occasionally the idle gets choppy. Car is making 20 psi of boost but feels sluggish. I don’t have any codes and took it to a mechanic and he found nothing wrong. Had my timing belt rechecked and it was deemed good to go. I did pull the valve covers and vacuum pump etc when doing the timing. Any idea what could be wrong. Not picking up any misfires either.