Spark Guide

I bought my 2014 Chevy Spark brand new back in April of 2014. After the first year or so, I occasionally started feeling like a hard shift and squeaky whining sound. Also, when at a complete stop I accelerate and it is very sluggish. Kind of dangerous when making left turns against oncoming traffic. I took it to the dealer twice and they said nothing was wrong with it. I recently went out of town and on the way back home, on the freeway, it felt like it got stuck on a gear. I would take my foot off of the gas and gently re-throttle and the rpm's were really high. I had to pull over, set the vehicle to park and turn it off, turned it back on and my check engine light stayed on, then, I continued home. My car barely passed the 46k mark and I'm having these issues. I'm worried that when I take my car in this Monday (soonest available appointment) they are going to give me the usual, your car is fine, pitch. My bumper to bumper ended at 36k. Will this be out of pocket? What can I do?