Mercruiser 140 sputtering and dying past 1500 - 2000 rpms

I don't know much about motors and such and this is a new to me boat but I would appreciate any input or direction in identifying what might be happening or what I should be considering in diagnosing a problem that has suddenly occurred with the motor in my boat.
So here are the details: I took the boat out this weekend on Saturday morning and spent about 30 minutes or so driving it the fastest that I have since receiving it. This was about 30mph - I don't know what the rpms where. (I know that's not fast to most but boating is new to me so I am learning things one step at a time). I have taken the boat out 5-6 times before and only moved around at more like 10-15 mph with maybe just a short burst of speed here or there - never had the slightest issue. After the second little burst of travel, I noticed that there was a certain spot in which when I had the throttle, the motor would begin to sputter - one time completely dying. If I simply pushed past that spot, it would sputter a bit and then 'catch' and move on. End of story for that day.

On Sunday evening I again took the boat out however now it absolutely dies if I throttle it up past 2000rpms. At somewhere between 1000-1500 it begins to sputter. It will continue and I can coax it up to 2000 but if I move too quickly it will die and if I push past that point it will die. It immediately starts back up w/o fail. I tried easing the throttle up, pushing the throttle up quickly, and kind of alternately 'revving' it up then pulling back and it would not exceed 2000 rpms in any of those instances.

Can anyone comment on ideas of what sort of issue this might be? I will provide answers to questions but am not sure what else to communicate in an effort to identify anything. I don't know if I am looking at a simply maintenance type of issue or some major piece needing attention. I got home to late in the evening to do anything at all and don't intent on tackling any kind of real issues but I would love to begin learning about basic care and small maintenance and repair rather than blindly taking to someone. Plus it would be so much more enjoyable if then and there I at least knew what to consider as being a possible issue. Right now, I am completely mystified.

thank you!

I am a certified technician , and I would sugest that you find a person who is schooled in Mercruser engines and drives. What you describe sounds like a shift interupter , that is not adjusted correctly . It could also be one of two cables that are stretchedor even broken . You do need to know what you are doing when working with thes cables.

Now would that fit with the fact that when I engage the throttle there is a really noticeable bump when it shifts into gear?

All mercruisers shift with a hard thump , but the interupter allows the clutch to actually shift it. Depending on the interupter adjustment it could advance the throttle beyond the ignition interupter. the engine ignition is shut off for a split second alloeing it to shift , if it didn;t you would not be able to shift it.

When you shift into foward gear and then give it throttle and then dies completely the interupter is pulled all the way from the interupter cam. You can open the engine compartment and watch the interupter. It is mounted either on top of the valve cover or in newer models it is on the side. Just follow the throttle cable to find it.

Correction , follow the shift cable actually. It runs beside the throttle. A shorter cable goes thru the transom to do the actual shifting. I hope this helps , Find a mechanic that knows Mercruiser.

Man, that's GREAT information BG - thank you!

Will do on the mechanic.