This is what I'm wondering on my 87 2.9L Ranger too. I'm having the same issue as Cees Klumper describes....I thought fuel injectors, but if that were the case I'd think the power loss would be all the time, not just certain times, and random conditions. Just hate thinking about the mess to get to that fuel pump in the tank as I'm leaning towards that as being the problem as well, maybe not failed completely but intermittent. Going up the hill out of town I have the trouble, possibly caused from that reservoir running out of fuel, and the in-tank pump not having enough pressure to keep that reservoir full so just about at the top of the hill it'll lose power and start bucking, and starving for fuel, then if you floorboard the accelerator it'll pickup and and be fine....maybe a combination of both injectors and that in-tank fuel pump being weak.