Re: Sputter
If I had these symptoms, I would first do the link and sync to make sure everything is adjusted correctly. I would then set the idle jets according to spec. If the stutter continues, I would adjust the idle screw in or out 1/8 turn at a time to see if that helps. If it does not, return the idle jets back to spec.
Next, I would check the vacuum in the fuel line to make sure there is no problem with fuel source. Check out the following link on how to do this.
http://www.marinepartsman.com/Mercury-Marine-service-bulletins/Mercury-Mariner/2001/EN_17.PDF
If the above does not help, then I would consider testing the ignition system. My preferred way is to use a SmarTach meter to check secondary voltage on each spark plug cable while under way with the motor sputtering. The meter would indicate if any cylinder(s) are missing spark or have a weak spark. There are other tools that can be used to check spark (i.e., spark gap tester, inductive timing light, etc.) but I find that SmarTach is the easiest to use when the motor is out on the water under way and sputting. If you do find a problem with ignition, then you would need a DVA meter and an ohmmeter to check out individual components.
Of course, others on the forum may have additional or better advice than this.
