my rs will start no bother, idle no bother and if i take the revs up slowly go all the way up and if i am hard on the throttle it pops, bangs, backfires and generally wont rev.

ive changed the plugs and they were very sooted up
changed the coil pack and leads as i thought the coil pack was breaking down under load but no joy

its not smokey but does have a strong petrol smell coming out the rs end

any ideas?