I don't think it's a misfire.

Bear with me here.

The problem only really occurs whilst at low throttle input, most noticable in 2nd gear whilst accelerating steadily, and is intermittent. It's sort of a jerky feeling, similar to what I experienced when my MAF was shot, but not as harsh. Revs back right off straight away upon releasing the throttle causing sudden extreme engine braking. As you can imagine, it's not pleasant to drive.

 

Now for the history.

A couple of weeks ago, whilst giving it the beans, the clutch pedal suffered the common break of the weak spot welds, resulting in pedal to the floor and AA recovery.

£37 for the parts and a few hours contorting myself into the footwell and all is well. Or so I thought. However, this is when the problem started. Car has been wonderful for the 4 years I've had it, no running issues after sorting the MAF.

Even with this problem occuring whilst driving, there are no idling issues, smoother than a baby's shaved bum as it has always been, the revs never fluctuate on idle any more than they should.

Upon re-reading things about the clutch pedal replacement, I've noticed something, that may show where my problem stems from.

My master cylinder pushrod was slightly bent, which at the time I didn't think would be a problem, despite people saying they had straightened it, however I now think this could be the cause.

Due to this the pedal doesn't sit as high at rest as it did previously. This, I noticed after a feel around yesterday, means the pedal is not fully pushing in the clutch pedal position switch. Maybe 1-1.5mm against the 5mm of travel that's available. From what I can gather about this switch, it tells the ECU that the clutch pedal has been depressed and drops the revs enough for a smooth gearchange.

Now my thinking is, if this switch is not fully pressed could this cause the ECU to think the clutch pedal is actually pressed down and be trying to cut the revs for a gearchange? There seems to be limited information on this switch on the web, but I can't help thinking anything else would be too much of a coincidence.

You could try cleaning the throttle body first. Its easier than contorting yourself again and what you describe sounds like a dirty throttle body

^^I thought that too reading the first paragraph, clean it and see what it sorts.