VW Golf running rough.

Hi there,

I have a VW Golf 2003 sport 2.0.

I have had this problem for more than an year now, and has really broken my trust in VW's.

My mechanic has not been able to solve this and I am trying to find who can or atleast some guidance.

This does not happen all the time, but mostly when the winter kicks in, I feel.

Basically the problem is, the engine is running rough. But to explain in detail, there is a lot of black smoke being puffed out and it smells like sulfur, the engine kinda of misses and feels like it's going to stop, but never does. On Idle, the miles per liter display shows 3.4 to 4.0. Per 100 litre as opposed to 1.2 to 1.4 when nothing is wrong. The computer also does not give any error codes. Once it did say that one of the pistons where not working and that's why I replace the plugs. The problem came back after a few months though.

Fixes:
I have replaced plugs, ignition cables, sensors O2 (the one next to the airfilter), temp sensor, air filter. I have done a throtle body clean a couple of times.... and my mechanic has basically run out of options. So I am asking someone in the forum to guide me to a better vw mechanic or some ideas as to what I should do apart from selling this. I am hoping it's not the central computer thats busted.

On a side note - there is a quick fix for this that my mechanic does. He would reset the engine computer each time this happens and then it would be good for a couple of days or even months. I did a reset a few days ago becasue it started running rough but, this time it went bad again in about an hour.

I live in melbourne south. Any good vw mechanics for this sort in that area.

Also I havent been to the dealer, and that would be the last resort, which I am very close to doing.

If not for this the car is really great. Any help please.

Thanks

K