I'm not sure what the title of this post should've been but, I was hoping you guys might have some insight as to what this might be. I've noticed, multiple times/random times, the car struggling to go from a stop. Most of the time, its noticed when letting go of the brake pedal and the car begins to move on its own in the small time before stepping on the accelerator. I'd like to describe it as its chugging for a second or two before it all settles and the car takes off. It doesn't always happen.
I will add this bit of information as well (not knowing if it has any relevance to the above topic but, just in case....)
When I first put gas in the car, I put "regular unleaded". The car struggled with going a LOT of the time but, not always. There was a very noticeable delay in vehicle response after stepping on the accelerator. If I tried sport mode, the issue was almost negated completely. Well, the next fill up, I put in premium or super unleaded with the 92 octane rating. The change in behavior and take off was almost night and day. It's take-off performance is pretty much normal now except the above mentioned topic.
Anyway, that's what I have going on. I'm considering taking it to a dealer for potential warranty issue. He "warned" me about my new wheels/tires as not being factory spec. I went from 16" 205/65/16 to 17" 225/50/17. I told him, I only got these wheels/tires the day before and this issue was happening long before that. He said, his techs would mention the wheels but, if they can see the acceleration issue isn't tied to tires/wheels then I should be ok.
I wanted this community's input on what they think it might be. =)