I've used nothing but Bosch in my 2L and never ever had any issues.
Owner reviews for spark plug
Anyways, I put in so Bosch Tri-Electrodes and Beru coilpacks. Once I got the APR ECU back the car fired right up. I drove it for a good hour and no misfires!!!
first set i used were NGK R5671A-7 non-resistor plugs gapped at .025\" had ran multiple sets of these for well over 20k miles with zero issues.
For the misfiring check your spark plugs it can be that simple... i got a mkiv golf too.
In my B3 Vr6, about 3yrs ago, I swapout the NgKs to Bosch Fusion 4-prones and my mileage went from 17 or so to 32mpgs. My car responded better and better mileage.
I have now used those plugs of mine up to 35psi so far with no issues.
Same exact plugs I use they haven't given me any issues I have em gapped to .022 and no misfires at 31psi, the car made over 600whp with no problems with these plugs, and they cost about $3 a plug.
Bosch FR8DC+ perform well and you won't have to worry about seized plugs. You might have to change them sooner.
I'm a technition with many years under my belt.... and had numerouse out of the box brand new BOSH plugs that upon installing them were dead, not just one but two in the same set, i would then take em out, check gap, and spark test the plug wires and coil, swop them to a diff cylender and bam.. still crap, im not trying to knock them and im not and NGP rep, im speaking from experience
iv had mor problems with a brand new bosh plug then any other plug.. even cheap knock off checker brands...
Write your review about spark plug
Help others - share your experience with this part.