The dealer told me when I drove it off the lot yesterday that he is happy to work around any concerns I have if they should arise but I need some advice first. I have noticed a few mechanical things with the car in the three times I have driven it:

First, the Rpms drop by a hair for a fraction of a second randomly and sporadically while idling (O2 maybe)?

Second, today after driving for about 10 minutes, I went to get on it (Accelerate) while in second gear and it hesitated twice during fast acceleration (throughout the one acceleration). Today is colder then when I test drove it last, but any thoughts? Maybe also O2 or fuel injectors?

Lastly, I noticed a couple times a slight burny smell when i turn it off and park it after its run a while. It just had a oil and filter change yesterday morning (not sure if that matters). Thoughts?

Any help is much appreciated friends!