Kind of sounds like you might have an issue with a lean or rich fuel mixture. Where the fuel hose connects to the fuel mixer [carb] there should be an adjusting valve that could have a small hex head about 8mm to adjust your fuel mixture. Toyota's had different types of valves. Could have a larger hex head type bolt with a jam nut or it might have a round valve with 2 flat sides for an open end 11mm wrench. You sometimes have to look underneath the housing because sometimes it's hidden. When you find it, start the engine and press the gas pedal to the floor and adjust it either direction until it smoothens out and runs good. Good Luck

Trying to repair with out seeing truck is hard but in the back of the regulator there is a hose that goes to the regulator that hose goes to the resonator box pull that hose off and see if the truck has power l have seen that cause very slow pick up and a loss of power the box is there so at high speed it helps the diaframes in the regulator from vibrating.