Quicker & cheaper to simply interchange the apparently misfiring no 4 coil for one of either cyls no 1, 2, or 3 coils to test if the apparent misfire fault code shifts?
Our juddering, shuddering & kangarooing Micra was tamed with the TB mass air flow sensor unplugged & it drove ok with the corresponding CEL & even passed an MOT!
As the banger was 20 years old we were reluctant to spend £90 on a replacement OE spec mass air flow sensor some 3 years ago but with the MOT straight through pass & no additional fault codes I bit the expense bullet & fitted one.
Now 2 years on & another recent straight through MOT pass the 23 year old banger is on 85K & running just as good as it was designed & built for.
Happy days. 