1998 Rover 2 Series wont run

Hi I have a rover 200 petrol it was left for a week and I tried to start it last night but it was just wouldn't go so I top it up with some more fuel and tried it again but it wouldn't go so I rolled it down the hill and it back fired a ran but as soon as I took my foot of the accelerator it stopped so I tried some easy start in the air intake and it wouldn't go so I got a tow to the the top of the hill and rolled it again and it went but stopped as soon as I took my foot of the accelerator again so I leaned the distributor cap but didn't get any progress ca you try and HELP me out what I could try next

thanks joe