1987 Dodge Truck Maybe you can help?

I have a 1987 Dodge Ram 50 2wd 2.0L carb., When I go above 35mph with throttle full pressed it will cut off and the vehicle will start to move back an forth, front to back, like it maybe running out of gas, when trying to reach 40mph, making it impossible to do anykind of freeway driving also when going up hills it immediately drops in speed making it impossible to drive uphill (the max i've reached going uphill is 15mph ). I replaced the fuel pump, replaced the rotor an cap, new spark plugs (gap is exact), plug wires, new air filter, cleaned the carb, cleaned the gas tank (rid of buildup), adjusted timing. Running out of options, I can really afford much, so im trying to fix it best I can myself. Any clue or help would be appreciated. Thank You