2000 Mercedes Benz S430 replaced battery then no exel

I just recently replaced the battery in my car drove it for a half a mile, then cut it off when I restated it would crank slowly. After that I proceeded to put it in gear, after which the transmission engaged but the gas pedal is unresponsive. I pressed it to the floor and nothing no rums or exceloration the car just creeps along at about 5mph