New walker surging and using alot of fuel

Got a brand new walker with about 15 hours on it. I know something is not right. It runs strong and is an awesome machine but I know it needs something. When I disengage the blades, the engine is surging and that lasts about 2 minutes. When I idle down, it also surges and again takes about 2 minutes to smooth out. The machine is also going through its fuel take at almost double the rate of my older walkers.

I will be taking it to the shop soon as its under warrant, but I really don't...

New walker surging and using alot of fuel