Sta-bil is only good for 12 months max..and that's added to new gas. You can't add sta-bil to old gas..and expect to make good gas from it. With 13 month old gas..and 3/4 of a tank..... I'd top it up with 93 octane. Then you have at least diluted the old crap a bit. Then drive it, till you are down to 1/8 of a tank, then re-fill with more 93 gas.
With gas that's 2-3-4 years old, drain it, it's crap. All you end up doing is clogging up injectors etc. You can tell the difference between fresh gas..and old gas... just take a whiff of it with your nose. Old gas smells rancid.
If you ever plan on not using the car over the winter..or longer, add sta-bil at the same time as you last fill up.
On my 2010, it has a fuel filter..like gabe shows in his pix above. One day the car would gag whenever I tried to get into boost, even with just 1-2 psi. Turns out the 'sock' filter that goes over the bottom the oem fuel pump was completely clogged ! The sock filter is just like a fine mesh plastic filter. Bottom of tank on driver's side had all this misc crap floating at the bottom of the tank...and the bottom of the sock is sitting just a hair above the bottom of the tank. Once that was all cleaned up, eng ran fine.
Just a few weeks before the eng started gagging, the FPDC (fuel pump duty cycle) was sky high, like 94-96%. Installed the 10 gauge wire mod from battery post, through a fuse, then to trunk area. FPDC didn't drop at all, it got worse, went up to 98%. Then it stated the gagging one day ( only when above 0 on the boost gauge). When it gagged, FPDC was pegged....also the fuel rail pressure dropped down to just 5 psi.. ( from it's usual 40 psi). Once the sock was removed and cleaned..and re-installed, we had to prime the fuel pump by putting key to...'key on, eng off position' for a few secs..then repeat several times, till no more 'whirring' sound coming from fuel pump.
Ok, then everything was fine, FPDC dropped down to 38-40% at idle..and no more than 80% at 6.2 krpm. Fuel rail pressure stays put at 40 psi, whether at idle or 6.2 krpm. With key on..and eng off, the fuel rail pressure sits at 50 psi. Start eng, and rail pressure drops to 40 psi asap.
BTW, steeda's version of the fuel filter for the 05-10 cars is made of SS, designed to handle E-85. It also cost less than the oem filter. Never used one, but did come across it on their site years ago.