Hi all....

I have a strange problem...3weeks ago ive put some new 071 plugs in the engine...so far no problem...
But yesterday...the car was running on 3cyl again when at idle...but when im driving it runs on 4cyl....
But if i bring the boost up above 0.5bar or so...it misfires...(i think the cylinder its about i guess)...
But otherwise it runs ok...only at idle on 3...

Does anyone have an idea...