corsa 1.2 02 reg when car is idling i can feel a miss and the rev counter drops a rev and back to normal and when driving especially up hills i can feel a little miss like lack of power no dash lights on also put code reader on nothing cars done 52k and this all started since i changed plugs and oil change
sounds daft but have you possibly knocked one of the plugs whilst fitting them... you could have closed or made the plug gap smaller just check and adjust if necessary with feeler gages...
or you may have dislodged one of the vaccum pipes..
failing that check the ht leads then the coil pack for cracks