Car came in with misfire and engine light on, the customer had his "mate" look at it and read the fault code with his "phone" amazing things phones.They put new coil on but still had misfire,we have got it in today read all codes recorded then cleared and road tested,the light stays off but there is a misfire, then after about 5 min light on and flashing, read codes and just get P0300 P0301 random misfire and cyl 1 misfire, we swaped coils over changed plugs and still the same, checked wiring, checked for air leaks fuel looks ok , but stuck now has any one any ideas thanks Steve