When you say misfire is it missing or is it a backfire from inlet. backfire check for air leakage between
MAF and throttle body
Missing can also be caused by a weak or broken valve spring which performs at idle but not above. When its a mechanical issue it usually takes out the cylinder diagonally opposite on the coil pack and you should have coil pack fault codes registered on the
ECU.
Of course this is on the outside but not uncommon but check all the other possibilities first,