It needs a tune up.
Usually a sputtering muffler means that a new catalytic converter is needed. The sputtering sound is the car misfiring.
You go to a mechanic!
If a car is sputtering at high RPMs, the fuel pressure needs to be checked. If the fuel pump can't keep up, this will cause sputtering. Also, the car should be checked to make sure the valves are adjusted properly.
Timing issue, poor ignition.
Anton de Haen died in 1776.
Anton de Haen was born in 1704.
I sometimes sputter when I'm nervous. Please reword the question and tell me what year and engine and describe what you are doing with the car when "sputtering" occurs. Would help if you can think of additional description of what you mean by "sputtering".
ggd
see CarTalk.com
Abraham de Haen died on 1748-08-08.
Abraham de Haen was born on 1707-04-06.
it will feel as if you are running out of gas, the car will start sputtering.