1987 Bronco II 2.9 Engine. Had it for 10 years with the same problem the whole time. Runs fine while the weather is warm and dry. Once the humidity or temp changes, or the rain starts, it loses power, bogs down while on the freeway. I have to feather the pedal constantly just to maintain a steady rate of speed. I've had it in the shop twice. They can't seem to figure it out. I've replace both fuel pumps, the fuel filter, and the fuel tank. Need help please before I do something expensive.