My car wont start

I have a 1989 chevy camaro I-ROC with 120000 and its a 305 5.0 I had it for about a year and been trying to fit it my problem is it was starting fine but I ran out of gas and it didnt want to start any more the only way it starts is by blowing gas in the intake I changed the fuel pump and filter, checked the fuel lines, and fuel pressure I dont know what to do I have tried manny different things the only problems I have had since I got the car was starting it and it runs real rough th engine stalls and dont up shift