New 2003gt... could it have a tune?

Hello Matt!
Been hanging around here for a while, but this is my first post.
I had to reply to this because I went through a similar headache. Similar because I knew I did not have a tune because I bought my 2000 GT (man) new. I started to have a pinging problem around 35000 miles using 87 (I only have 50000 on it now, low mileage!). Going up hills on freeway without it pinging was hard, anything more than just off idle and it pinged, 4th or 5th gear. Tried 91 and it helped a little, but still there. I started with basic stuff that could throw off air fuel ratio. Changed fuel filter, cleaned air filter, looked and listened for vacuum/exaust leaks, changed spark plugs, tried Seafoam, everything helped a little but nothing cured the problem, still pinging up that damn hill.
Well, a few times when coming to a stop, my car died, I knew it was about time to get a new battery so I dropped a new batt in and my car felt way better, so I got on the freeway and went up that hill and what do you know, NO PINGING!!! Now was this just a coincidence or was a weak batt not providing enough juice to the coils and fuel injectors? At the time, it was the orignal factory batt and it was about 5 years old, so you might want to have your batt load tested. If you have a tune or not, maybe someone else will chime in to help you there.
Good luck with the ping and I hope this info helps you out!!!

Wow I would have never thought it was the battery. I was reading your post and trying to figure out what it could be lol.