cutting out and poor starting

Have a little problem have a US import Nissan Quest 1994 model here in spain, starting is very erratic, miss fires, runs lumpy until warm, sometimes just cuts out altogether whilst driving.
Anyone had this fault, auto electrician cant find anything wrong, could it be the computer? fuel pump? please help...live on top of very steep hill, not much fun when cuts out at 40 mph, no power steering or brakes.
Also have trouble finding parts supplier in US that will ship here.

Thanks to all that respond in advance.

check base timing

change spark plugs, fuel filter, o2 sensor.

Do these things one at a time and see if that helps. I'm basically telling you to do all of the regular maintenance on the van.

There is no Nissan dealership in Spain? I know there was a place in Sicily. Try e-mailing someone at Nissan (use the official website to find a good address) or e-mail a US dealership and ask for a good place to order your parts from.