When driving slowly at small roundabouts etc. the car can lurch badly usually between 1500rpm and 2500rpm. I think its in the limbo area, not accelerating nor decelerating, it is hard to tell as it is only for a split second. It can happen further up the rev range it is just less noticeable. First gear shows the problem the most. The car also runs rough on start up. The car was not heating up properly but I have since replaced the thermostat and sensor. The car now sits bang on 90 and gets up to temperature quite quickly. I was hoping the two problems were related but sadly the blip is still there. The car has been hooked up the machine but no fault codes are present. Can anyone shed any light on this problem?