I was going to adjust mixture, but a friend said not to do this without an exhaust gas analyser attached. I'm going to try and get this done tomorrow. BTW I was checking connections to various sensors etc and found a partly broken wire leading to a blue 2 pin connector in between 2 injectors, after reconnecting it car ran richer than ever!
That would be your coldstart valve.I think your CIS-EZL coolant temp sensor may be faulty, causing the coldstart valve to be operated even after the car is warm.You can check resistance values at the sensor to confirm this.When cold you should see very high resistance in the kilo-ohm region and then when warm, say 80 deg (abt 300 ohms in my car).
It it is faulty,that was probably why it was disconnected.I don't know if the coldstart valve is leaking but you should check it just to be sure.
Then, with the coldstart valve disconnected, the car would experience hard coldstarts.In order to mask this problem, the mixture was probably richened.
If the coldstart valve is indeed leaking, it would cause the car to run richer than normal and coldstarts would be no problem even with the electrical connector disconnected.
Check out these 2 components, then, when sorted out, you can tune the mixture by duty cycle at pin 3 of X11 connector on the left fender in the engine bay.