G16 Go problems!!!

[Hickman]

My g16 started acting up yesterday. Gas with brand new battery and rebuilt starter. Before yesterday it ran perfect now when you push on pedal it surges and bucks and usually wont start but, it will start in reverse but runs rough. If it does go forward it is at full throttle only and isn't as fast as it should be. Where do I start? Acts like it isn't getting the fuel it needs but that doesn't explain why it will run in reverse. Any help is greatly appreciated, we use it daily on the farm for chores.