Please help! Truck cutting out on hills.

So I just got home from a fishing trip about 4 hours from home into the foot hills. On the way there, I almost turned around and went back home.

What is happening is at highway speeds, every time I start up any kind of hill, even just a bridge, as I would start any climb, the truck would start cutting out as if it was running out of fuel. If I let up and coast down to about 40 mph, then start to gas it again, it would be OK. Unless I was still going up hill. If I was still climbing it would go OK for a minute or so and then start cutting out again. If I tried to keep an even speed up the hill, it would start dieing.

It seems like it might be having a problem keep the injector oil pressure high enough. When I put the motor under any kind of heavy load, it cuts out. On long flat sections of highway, held at a steady speed, I had no problem.

I thought it might be the MAP sensor so I tried unplugging it and driving a while. Same problem.

Could it be the injector oil pressure regulator? I have a dual HPOP, (Stealth), so I dought it could be the HPOP, but who knows.

Just so you know, I have new fuel filters and a new fuel pump, (Beans fuel system), and I checked the fuel pressure a few times. 60 psi. I also just changed the oil recently so the oil is good.

One other note. Every time this would happen, the speedo would start bouncing a little. So I was wondering about the speed sensor also. Not sure if the speed sensor could make the truck cut out like this and I could not see how the speed sensor could only have problems going up hill but I thought I would mention it.

Any help would be great. I have another trip planned for next weekend so I would like to figure this out soon.

Thanks for any suggestions.