1999 Ford Taurus My car has stumped everyone.

Engine Mechanical problem
1999 Ford Taurus 6 cyl Automatic 119767 miles

I went to start my car a few days ago, and was somewhat unsuccessful. This is what happened:

-When it started, it sputtered and fluctuated around 500rpm. It's usually around 1000rpm.

-When I idled it to 1000rpm, it felt and sounded normal. When I wasn't on the gas, I heard a squeak from the alternator, but the belt was on track. When I let off the gas, it ran a little bit and shut off.

-Before it died, the dash lights and clock flickered when I was on and off the gas. When it went out, the battery light, oil light, and the service engine soon light came on.

-I have recently changed the oil, cleaned the fuel injection, replaced the fuel filter, and filled my gas tank. I don't think it's the battery, it's only a year old. No weird smells, but I'm hearing a tick from outside and a squeak in the alternator.

I've had lots of ideas, but most everyone I asked had no idea what's going on. I'm thinking alternator or computer, but don't know for sure. If you can help, please tell me. Thanks.