renault scienic 2002?

last wk I went 2 start car an the battery was flat so had 2 get started with jump leads when it started it sounded like it backfired an smelled of petrol abit been fine for 10 days or so then yesterday I was driving, an the car started 2 judder like it was about 2 run out of petrol which I thougth it was as I let the petrol get very very low, then the emissions light come on went put petrol in but the emissions light is flashing on an off an when driving it was loseing power when I accelerated so haven't drove it but started it for 10 mins afew hours ago an it sounds like the exhaust is blocked or sumthi any help would be good thanks