2014 model suddenly running rough

Rather than putting up with certain people here, just click the "ingore" feature. Then you won't
see them.... You're life will be better for it...

 

Assuming the engine is still running without a load (not common) perhaps the damper is damaged between the engine and transaxle. Caused by the head gasket misfires. We have heard of one or two failed dampers after excessive misfires. Damper repair requires pulling the engine. Normal head gasket misfires also cause severe metal to metal sounds that is the damper slipping as designed.

 

In fact, misfiring from any cause will make the same noises and, if sustained long enough, damage the damper the same way.

 

There’s a black plastic panel at the junction of transaxle and engine, accessible from underside. I believe you can pry that off, check for damper spring remnants, and also rotate crankshaft (with an assistant), observe damper plate while rotating?

 

I'm not sure there's much you can observe of the damper plate, on the other side of the flywheel from what you can access through the little hand hole.

But if any spring bits have fallen down to the bottom of the housing, you should be able to snag those with skinny fingers or a magnet.

 

The spark plug concern can't be stressed enough. The market is flooded with counterfeit plugs. Lots of people say they'll seem ok up to 5k miles, then they self destruct.

You really have to rely on dealerships and very trustworthy parts suppliers for spark plugs. Even the kids working the counter at your local parts store know how to make an extra $20 an hour. It's a big problem.