starting cavalier

few weeks ago my cavy started idling hard and the check engin light came on. i immediately pulled over to check it. nothing seemed wronge so i continued home for further inspection and the idleing resumed normal idle. then the problem progressed over a week and now it idles hard when started and will smoke slightly from the exaust. then after a small amount of reving it resumes normal idling.

NOW it wont start the engin turns and does not start.... i have replaced the plugs and it worked fine for a week and then went back to this i replace wires and i replaced fuel pump and filter i have had the injectors cleaned... what else could it possibly be? there is gas... there is fire... why is there no combustion?

help please?

some thing plugging up ? catalytic converter ? doubt it bought maybe