I had the dreaded shaky idle + engine power down (half-engine symbol) a few weeks back. Took the car in.
They ended up replacing three injectors plus associated spark plugs, and updating the software.
The car now has much much smoother idle than before. And get this: I'm getting +4 MPG average from before the fix!
I used to get 20.x MPG, I now get 24.x MPG under the same conditions....
So there's that benefit, at least.
Always laugh when you can. It is cheap medicine