Try cleaning your mass airflow sensor

 

Two other things to checkout, see if theres any cracking on the intake tube. The rubber is ridiculously terrible and fades/cracks easy as has happened on previous mazda vehicles and still has not been corrected to this day smh. The other, although not sure how relevant it could be, possibly something with the fuel system. I would suggest running about 1.5x the amount of seafoam through the engine in the fuel tank. (add in when almost empty, add in the '1.5x amount of what should be added for a full tank, drive around for a mile or two and then fill up at gas station). I would suspect maybe a dirty injector didnt spray enough and caused preignition? iirc our mazda has a higher compression ratio than average vehicles and its been an occasional problem for cars which havent been periodically cleaned through.

As unfortunate as it is to say, dealers are pretty bad at fixing anything once its out of warranty and you enter the 'trial and error phase' where they will basiclaly try random things, bill you for it like its gonna fix the problem, then when it doesnt which is very likely, repeat the process all over again


edit: Now that I remember, your issue feels awfully similar to an old coworkers bmw (manual) that would struggle and stall out when he put it in neutral after dumping rpms out of a gear. We ran some extra concentrated fuel system cleaner and maintained high revs to force it through (not recommended on auto transmission in neutral) and it fixed the issue.Fuel pump was working perfectly and this issue was noticed a while before the stalling when the engine would struggle whenever in neutral (or in our case braking to a stop) it got progressively worse to the point he couldnt leave work because turning the car on would go crank, fire up rpms in the initial rev then drop out to a stall. May or may not be relevant here but couldnt hurt to pursue this route of maintanence,

 

Last time I talked with the dealer they told me it's normal for the engine to shake and RPM's to drop,

this is also code for we dont know what else to charge you for because you will notice we are just billing random service we dont know what were doing so we say its 'normal' 👀

 

 

Update. I took it to a different dealer they did tests and we drove it around.The mechanic seen and felt the issue but the test said everything was within limits. I got them to clean the mass airflow and throttle body, it seemed to run a little better after that but now it's back to being pretty bad. I have not done the seafoam yet but have used Heet and other fuel injector cleaners. The mechanic at mazda said he didn't think I should put anymore cleaners in my gas. I'm wondering if it could be the Idle Air Control and tried to look that up online but couldn't find the part to purchase or a schematic, any ideas?

 

To my knowledge heet deals with water in the line and 99% of regular fuel injector cleaners dont really do anything. Keep in mind the two most popular proven items that work at actually removing deposits are seafoam products (a carburetors best friend) and cleaners with polyetheramine "PEA",anything else even if its been a previously popular brand like techron or gumout is not to be trusted unless it explicitly says contains PEA . Gumout specifically started changing the termimology on their cleaners and removed all mention of pea on new bottles which means they probably switched to cheaper cleaners that burn through like nothing. Seafoam is a special case as you can theoretically run an engine on it exclusively on low load but would cost ridiculous amount since expensive per bottle.

 

Update: just got the car back from the shop again. This time the check engine light was on and codes said P0300, P0304 misfire and P0171, which is system too lean bank 1. The dealer determined my fuel injectors are bad. They replaced them and the issue got slightly better but is still present. Here is a video of what my car is doing with A/C off and parking brake on while in drive. This is me pressing and releasing the brake. Any ideas? New video

 

Hey there, hope you are well! I also have a 2016 CX-3 Grand Touring, bought at 41,000 miles and currently at 121,300 miles, however I have the EXACT same issue with mine! Noticed after starting it two days that it was shaking while idling/low RPM. Check engine light comes on shortly afterwards. I take it to a shop yesterday to get it looked at sooner due to my local Mazda dealer being backed up for a little over a week. Was recommended to replace the spark plugs. (which were definitely due, the plug for cylinder 3 was very dark, the other 3 didn't look too bad.) Long story short, new spark plugs in, doesn't fix the issue. They check both of my ignition coils and even swapped them, didn't fix the issue. Still have my appointment with Mazda next week.

Was wanting to see if you ever found anything out and/or figured out what the solution was with yours!

Thanks!