Persistent misfire

I bought a 2000 2 litre petrol Golf about a year ago. It quickly developed a misfire when under accelleration at low revs. If I gun the engine then it brings up the check engine light and sometimes the red no charging light comes on for a split second. It does however run perfectly smoothly when cold, and only develops the misfire once the engine is at full running temperature.

It has had a full service at a VW dealers - they told me that 'they all do this' which i simply don't believe. Two weeks ago I took it to another dealers who, after bragging about their $70,000 diagnostics machine, told me that i needed new spark plugs and leads which again i didn't believe especially as they wanted to charge me $340 to do just that. I have subsequently checked the leads and replaced the spark plugs with no effect although bizarrely an oil change seems to have made the problem a bit bettr though not cured it.

I assume that the problem must be related to one of the changes made when the engine is running cold i.e. on the choke. I am not familiar with the effect of the engine management system and don't know if the running is simply made richer for start up and cold running or other things such as the timing are affected. Does anyone know? If it is fuel mixture only then it can't be something electrical, QED. But if the 'choke' does affect the timing then it could conceivably be electrical.

I was thinking I might change the coil next or take it to yet another dealer to try and get some sort of sense out of these folk.

Any thoughts on this would be really welcome.

Cheers

Gary

spray water on the plug wires and coil when the engine is running and if it arcs or misfires replace them. if it doesnt than its not bad.

Also you sure its not the red "oil" light coming on?