Water may have been mix with the fuel

If this is case that this all started after adding this fuel then I would suggest draining the tank and filling with known good fuel. Water in the fuel can damage the engine, not only cause issues with acceleration. However, if you are low on fuel, then you can try adding an additive that will absorb the water and pass it through the engine. If you have more water than fuel at this point, you will need to drain the tank. At this point, it won't hurt if you top off the fuel and then add the additive to see if smooths it out.