Today my wife and I took our skis out, she has a 2011 GTX 155 with 38h on it, bought it brand new and it's running really bad, not sure why:

it started like it had a dead cylinder, it would only go to about 5000 rpms and 38 mph, then all of the sudden would pick up in power (like the missing cylinder would fire up again) then did that for a while. Figuring it wasn't bad gas (ski ran the weekend of july 4th, ran perfect) since we filled both of them up right before going out (mine ran fine), I tried troubleshooting it on the dock:

Started it up, and pulled the coil connectors one coils at a time, one of them felt like it wasn't firing at all (no rpm drop or sound difference when unplugged). So, I pulled the coil out, see if there was anything burn or abnormal, and decided to switch it with the middle one. Put everything back on, fired up and felt like all cylinders were hitting, took it out, ran great, so out we went. We were out for 2h, in the rough, and she had no complains, said it ran great.

On the way back it did the same thing, to a less extent...same loss of power but picking right back up, I'm talking switch on/off like, rpms stuck at 5000 then "switch on" power comes on and it goes to 7k just fine (you can clearly tell the engine sounds different every time, again, like it's dropping a cylinder)

Decided to pack up and went home, cleaned the skis, and once we hooked up the hose to it, fired it up, idled about 2400, I gave it some gas and it stuck at 4000 rpms. Shut it off, waited 30 sec, started, right to 4000 rpms.

I pulled all the plugs out, the outside were corroded, but the electrodes looked fine. Cleaned the plugs off, put them back in, fired it up, idles at 2400, gave it a couple squeeze, and to 4000 rpms it went. At that point I gave up, it's gonna go at the shop monday, but I was really wondering what could cause all this trouble.

I know it's not the gas, my Yammi VXR ran perfect, and we fuel both of the skis at the same time, every time.
The GTX had the timing chain recall done on it, but, ran fine after that up until now.
No "check engine" light to tell me anything is wrong.

Any ideas on those two issues?
It does still have the original plugs in it, so I'm thinking it's probably that or a bad coil...?