am i suffering from pinking/knocking mk2 16v 89

[Diluxe]

right my car has developed a problem that i think from what I've read on this board is called "pinking or knocking", symptoms- running along at 80-90 mph theres like a misfire revs drop a couple of hundred rpm , loss of power then returns to normal, if i drop the speed below 80 or increase above 90 it doesn't occur.

it doesn't happen all the time , only seems to be on a long distant journeys,However it does sometimes happen around the 35-50 mph aswell, any idea whats causing this?

sparks ,rotor,dizzy cap and arm,leads are all fairly new.

cheers

[jezza16v]

Not pinking or knocking I'm afraid. Pinking normally sounds like a rattley jingling noise under hard acceleration around 4000-5000 rpm typically in a 16v. Might be an ECU or ignition module/coil fault, someone else will have some ideas but deffo not pinking... 

[carpetmonster]

Mine suffered from pinking on unleaded fuel so i was told to change it to the super unleaded.Its a bit dearer but it has stopped.

[Diluxe]

i did think coil, but it seems weird that i can drive through it