Water in the tank, more than likely .... not the problem.
When is last time you gave the car a tune up. I believe it's every 2 years.
Tune up your car will prevent many problems like this.
I would start with the air filter , if you not going to go with a full tune up
but replace these and more than likely your sputtering be gone.
1. air filter
2. spark plugs
3. fuel filter
4. distributor cap and rotor
5. spark plug wires
6. clean out carburetor or fuel injectors with an additive to gas tank.
Try these first before looking elsewhere
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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.
Usually a sputtering muffler means that a new catalytic converter is needed. The sputtering sound is the car misfiring.
A cylinder misfiring can cause this sympton, check/replace spark plugs and plug wires. Also, sputtering and shaking can be caused by engine timing, have the timing checked. Another cause can be fouled fuel injectors on fuel injected vehicles.
clogged fuel filter, or bad fuel pump
You go to a mechanic!
It needs a tune up.
It does not always mean that will happen, but it is certainly a common cause and if your car is sputtering and bogs down it would be one of the first things to check.
Timing issue, poor ignition.
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
A malfunctioning battery can't provide enough power to your ignition system when the motor is idling can cause sputtering. If there is not enough gas, that can cause your vehicle to sputter. If the spark plugs fail to fire will also cause your vehicle to sputter.