UNforgivABLE

My car suddenly stopped starting last week...

it just turns over and over and over but doesnt start.

Sometimes it will start for like half a second but then immediately dies, even if i keep my foot on the gas.

Ive changed out the spark plugs, reset the ecu, and tried jump starting just to make sure it wasnt the battery.

Any ideas? Car was running great prior to not starting, except it was running pretty rich at idle on my wideband....