2002 Jeep Wrangler check engine light

My check engine light keeps going on the code is low volts tps(but ive changed it out twice and still have the same problem(when ive been driving for at least 20 mins the check engine light turns on and the engine starts to stumble and almost stall when im at a stop) what could the problem be since it not the tps,what else could it be????? Im confused