If it was OK before you replaced the plugs and leads, you could put the old leads back on first and see if the problem goes away and if not put the old plugs back in as well.

As Keith says, put the old bits back one at a time if the fault didn't pre-exist, but I was under the impression this was an ongoing problem. It's the same route I initially took years ago. I can't recall what finally fixed it. I tried all the above and the engine temp sensor (easy swap over, with thumb over, slight coolant loss but otherwise easy). That didn't fix it. If she starts hesitating at junctions from stationary, on mine that was fixed by putting a new coil pack in (10 mins job, use torx keys, £70 part approx). Otherwise once you've ruled out the cheap stuff, it can be the O2 sensor (lambda) and other things which I've forgotten but a mechanic may post here to say what they are.

I recall also buying and fitting a new idle speed control valve (fiddly) and no joy.

I sold mine and can't remember if I still had the idling problem when I sold her or not, I will try to find the notes somewhere but right now no idea where they are. I didn't ever replace the O2, it was too expensive. I sold her when the exhaust went and couldn't be welded, I had just had enough of the car and vowed no more good money after bad.

Edited by Lee1 on 18/06/2010 at 13:51