Car is using more significantly more fuel lately. new spark plugs cleaned MAF sensor. no obvious fuel leaks. car seems to be underperforming at random times. What's causing the increase in fuel consumption? Fuel pump in fuel tank? Computer? Some sort of sending unit? Car not throwing any codes currently...fyi....

A fuel pump will not increase fuel consumption unless there is a leak,which you say there is none.a change in driving habits can increase it without knowing the habits have changed.some times poor gas quality can cause this or when a fuel company changes its additives when switching from a winter type mixture to a summer mixture.if the thermostat hasn`t been changed for a long time this can cause an increase if fuel consumption,as the coolant sensor will send a signal to the computer that the engine is not up to operating temperature and it needs to increase injector on time(spray more fuel).a tired coolant sensor(rarely),the throttle position sensor(tps)can cause this(on rare occasions)possibly a partially plugged fuel filter as you have to push on the gas farther to get enough fuel to accelerate the car.