Idling RPM variation

[spbutler]

I have a 2012 Evinrude 250 HO.
It seems like I hear and feel a quick slight miss when idling or traveling at less than 1000 RPMs..
I had it on the hose yesterday and was around 500 RPMs on the Digital I Command Gauge but it varies by almost 100 RPMS between 460 and 550. I didn't check it at idle in the water but it seemed to do the same thing when traveling slow.
I didn't know if it's the sensitivity of the tach or this is normal or something . I'm bringing it back to dealer but would like some input on this
I pulled all spark plugs and they are gapped and indexed properly.

[LIQUID NIRVANA]

What is your full throttle RPM with your normal heavy load?

[spbutler]

6000 rpms

[seahorse]

You cannot troubleshoot a drivability issue on a flusher, the motor needs to be in the water and the normal depth because it is calibrated for exhaust backpressure. On a digital tach, you will see a normal variation in rpm as the idle stabilizer circuit changes the timing and fuel flow as needed.

[spbutler]

Thanks, so now I just need to find out if it's really has a quick glitch or not. I spoke to my dealer and he said it could be an injector dropping out for a split second and it wouldn't throw a fault.

[spbutler]

No problem found by dealer. He did flash the ECM with an upgrade which is supposed to improve idling and starting, but it always started on 1 click of the key. When I picked up boat yesterday i did find a small leak on the output hose after the primer bulb right by the motor. I cut the hose back and replaced the bulb. Maybe this was causing the issue, if I even had one. On my old motor the bulb was in the bilge right by the water separator, they moved it up right before the motor when they replaced the motor last year. Not sure if that matters or if you even need one. Haven't had time to do a test ride yet. This may have always done this and I just never noticed it. It doesn't seem to be affecting performance.