I need some major help..

I have a 85 Nissan Pick-up with the 2.4L The problem is I start it up, runs fine. Drive it for about 10 or so miles and then there is a sudden loss of power. No matter what gear I put it in it is like in a fast idle. I then stop the truck, cut it off. And then it runs fine until another ten miles or so. Please please help me I'm losing my hair on this one. Thanks

could be a bad sensor somewhere. or your fuel system. the best thing to do is put it on a diagnostic machine.