Hey guys, not so new member, but first time poster. Here's the deal:

My baby, 2015 Infiniti QX70S, is struggling lately. At higher speeds, the engine seems to be working harder than it needs to, to get the speed that I want. Or in other words, the smooth, yet powerful rumble is now coughing along. I need to revive it...I need to let it live again. The good news is that there is nothing mechanically broken, at least according to my mechanic. I suspect this will require some combination of thorough cleaning and sparkplug change, but I don't really know where to start.

Have any of you experienced something similar, if so, can you direct me on where to look and what to do next? Admittedly, this is not my strong game, so I am a relative noob.

Thanks in advance.

If you don't have a check engine light, and there are no codes, then start with the basics. Change the spark plugs, air filters, and do an oil change. What does your mechanic think the problem might be?

He went drivetrain, not powertrain. In other words, I've got the beginnings of a problem with one of my wheel bearings. He also said I have a slight crack in my oil pan.