I just got back from the dealership and oh man I don't even know where to begin! Here's the story:
Per the advice of several members, I inquired with the service manager as to whether I could try adding a couple more gallons of gas since AAA only gave me a tiny amount (~1 gallon). She advised me against this, citing how it wouldn't work since the master tech has all this experience with Mitsubishis and I'd need to do the recommended $700+ repair. At that point I became so pessimistic that I test drove a new Lancer and talked about trading in my old, broken Eclipse (they offered me $2500 for it).
Here's where it gets interesting. As I was inside talking with the salesman (an hour ago), I heard the signature sound of my car starting! It's a very distinct sound cuz I have a Borla exhaust and headers, so it can be heard from far away. I run outside and to my car and to my excitement it was running and idling just fine! Only a little bit of smoke/condensation came out of the exhaust for a couple minutes. Man was I happy, it felt like the day 6 years ago when I bought the car. So guess why it was running? One of those techs had dumped a couple gallons of gas in it, probably because they needed to move the car at the end of the day.
I drove it home just fine and of course, gave it a full tank of Shell V-Power on the way home. Drove perfectly. I am just ecstatic right now. Not just cuz I avoided a very costly repair, not just cuz my recommendation turned out to be correct over what the sales manager told me, but I am now rescued from getting lured into trading it in and making payments on a new Lancer.
Time to sit back and celebrate this with a Long Island Iced Tea tonight!!
If any of you guys who gave your helpful advice were local I'd treat all of you to Long Islands as well. Thanks so much BITOG!