1997 Vauxhall Vectra losing power then stops

Hi hope you can help, Engine management light staying on, took to garage, they fixed couple of things, then said car needed new exhaust manifold gasket, also camshaft sensor not working, have replaced cambelt and manifold gasket, took it out today, was going fine on motorway then light came on again and car judders, then starts to loose power and then comes to a stop, turn car off for a couple of minutes, then start up again and it runs fine for a while, then goes again, I do not have much money and cannot afford to take back to garage, my son can do most things on my car, but do not know what is wtong with it now after all the new things we have put on there, please please help before oi scrap and have to catch buses.