Frend of mine have GOLF MK3 VR6  AAA engine code. A few days ago car starts to make little problems, sometimes at 2000 RPM at cruising speed, engine Jerks. And when you left foot of throttle it doesen't  deacelerate smoth, same is in gear (from zero throttle) when you press full throttle it have some delay than sunedly accelaerate. That is very rough
Problem is I can't connect via VCDS. On other moduls I can but on Engine there is no resposnse from controler. I connect only K-line, does L line have any  
relation with that?

I check wires from ECU to diagnostic conector, didn't find any problem