my car keeps juddering and losing power i have replaced the spark plugs and coils and had a diagnostic test done which did not show anything up im wondering if it is the compressons or ignition plugs thanks

shell, May 2010

Not an answer but just registering a similar experience in the hope that someone knows the answer.

2 Litre 8 valve petrol engine, new plugs, leads, MAP sensor.

SYMPTOMS: Starts brilliantly from cold and runs perfectly. If you then park up (eg, having driven a couple of miles to the shop) and let it stand a little while, on re-start it suffers classic fuel-starvation problems which, having coaxed it along on a light throttle to keep moving for 100 yards, suddenly clear and it then runs like a good-'un. It surely has to be a sensor?

Mike Rochester, May 2010