2003 Mazda B-3000 pick-up keeps cutting out.

check the fuel line for some kind of leak, if that doesnt work, then go to the engine, look for anything unusual in it. You may need to get dirty doing this!

Have you eliminated the fuel pump as the cause? You can make a quick check of the fuel pump by listening for a little whirring sound when you turn the key forward ( but don't start fully). If it makes that sound then there is fuel going to the engine. You can also have a friend listen for it if you are in a noisy location by sticking a long screwdriver to the metal of the fuel filler neck and putting his/her ear to it when you turn the key, again listen for the whirring sound.