Enginer Stuttering / shuddering at 2300 rpm (vit)

[jeremyisme]

My Vit seems to stutter or shudder at about 2300 rpm. It happens when my foot is at about 1/3 throttle. But goes away when I take my foot off or press it down full.

I have an air fuel ratio meter in the car, and I can see the mixture going normal, none (i.e. when the engine is at vacuum), normal, none really fast, coinciding with the shuddering.

Hopefully that makes sense
I am thinking it could be the O2 sensor playing up, but it doesn't make sense as to why it is happening at certain revs or throttle.

Any ideas?

[FullbackNo1]

mine is playing up the same way aswell will tell you when i find out wat it is

[jeremyisme]

Btw, does anyone know if you can connect the existing four wire O2 sensor to a standard single wire one?

I know that the four wire ones on the Vit, have a heater in them to get them up to temp faster, but there is still only one signal out, so I am wondering if I can just connect that to another single wire O2 sensor I have, and see if that sorts the problem out.