my ka wont start???

[vutony]

I have a '92 FB and the car would crank but wouldnt start......but when i add gas to it....sometime it will and sometime no...and when it does.....i need to rev it up to like 4,000 rpm and hold it for a little bit or else drop way down...i think its my alternator.....anyone inputs would help...thanks

[MS180SX]

have you checked your mafs and wiring? this happened to me once, and it was a pita to figure out, i just cleaned the mafs plug and was golden.