Hard to say what the problem might be - probably fuel mixture which is governed by the engine's management system. Worth checking if a good mobile engine tuner could help. Cost about �35-�40 for a full check and tune in my experience. Should be cheaper than a main dealer. Good luck.
ah but this also could be your piston rings... does it start at all when its cold! if so its your piston rings that have worn away, this may of lead to cylinder and piston scoring or similar.