Pinking 1.8 mpi golf?

[summers]

Hi all i've got a problem with my golf, when idling it misfires occasionally, when accelerating on the motorway at about 70 it sometimes missfires and seems to hesitate.
Also when accelerating it pinks quite badly, manly when changing gear, say change from 1st to 2nd and for one second it will pink then it'll be fine.
I adjusted the timing by moving the dizzy and the car performed perfectly it stopped pinking, the misfire went and it pulled strongly through all the gears.
About a month later all the symptoms are back and it's gutless and pinking again?
It has new plugs leads dizzy cap and rotor arm., i'm not sure what to go for next i'm thinking it's possibly the lambda as it also smells very rich on tickover.
Has anyone come across this before? any help would be appreciated,

thanks peeps

Ben

[Driver1.8]

I have a mk3 driver 1.8 with the ADZ engine code, experienced this exact problem until MOT time 3 days ago, when the emissions where tested, they were sky high, had the lamda sensor changed and all is now well with emissions and the car has stopped pinking. Also using less fuel as a result.
:biglaugh:

[summers]

excellent thanks for that, i'll change that next