My car is having roblems starting it turns over but will not fire up?

I have a vw golf 1.6 1997, after throwing alot of money to resolve this problem and having 5 mechanics still not find the problem im hoping one of you can. It turns over but will not fire up if it is managed to start it is then fine it started of on just cold mornings but has gradually got worse it was judering and stalling going down the road though that problem has seemed to of stopped im still having the problem of it not wanting to start! It was over fueling also but I have had new lambder sensor, rotary arm, ignition switch, plugs and leads, distrubuter cap I am now running out of ideas of what to do with the car as I can not afford a new one!