Need to check fuel flow into the carb. Remove the fuel line from the carb and observe the flow of fuel coming out of the fuel line. If not a full stream then there is an obstruction preventing fuel flow. and could cause the issue that you have because it is burning fuel faster than it can refill the carb.
also keep in mind that MTD likes to hide a screen in the inlet fuel pipe that cannot be directly accessed and depending on material lodged in the screen cannot be blown out with compressed are. So may need to look hard down into the fuel inlet with a magnefying glass and check for debris, and may need both compressed air and carb cleaner to get the stuff out of the screen. That screen plugging will also cause your issues.
