misfires after going downhill experts please help!!

[Adrenaline]

I have noticed that when the misfire starts happening if i give the car a full throttle it will run again fine but if i dont it will leave me sitting on the road waiting for a pick up
NEW HG HF downpipe to be installed tomorrow morning will see if it changes something

[Adrenaline]

Maybe be a bad valve cover gasket? When changing plugs i remember the third one of them was oily the on the cylinder causing the misfires

[Adrenaline]

Update on this went downhill in S mode the whole road and it same one were i used to get stuck late at midnight because of the misfire and i gived a wot from time to time and it seems that is fixing the issue but i am not sure that doing that trip on D will make me survive the trip