why does it seem like my infiniti isnt shifting gears?

It does require Premium gasoline, you are correct. I had an appointment with Infiniti today at 11am and I didn't want to pay the $175 for the initial diagnostic test, since I am real low on cash, but it seems like that may just be the best solution at the moment. Im not sure what the code was, but I had initially taken it to two different mechanics to see if they could run the tests and they checked the "check engine soon" code, but they didn't give me the code. They both told me they werent sure what the issue was and one said it could be transmission and the other said another issue. So I think taking down to Infiniti is the best idea at the moment.

ok,it's up to you.AAMCO use to to and maybe still do scan your transmission for problems, free! if you want to try them,i believe it's still free for the scan there.you DON'T have to have it fixed there if there is a problem with the transmission..also a good shop with a good scan tool with live data is going to charge you somewhere in that dollar range for that service,BUT it keeps you from throwing parts/money at your car!