these cars actually have a timing chain, not a belt. also, if the chain was broken, it would not start at all...
as far as all of the replaced parts go, were they actually bad, or did were they just replaced hoping that they would fix the problem?
as far as the car not even regestering on the diagnostic machine, is it the right one for the car?? if it is the right one, I would would maybe start looking at the PCM.
but don't just go out and get a new PCM just yet, wait untill you get some other opinions from others as well.
relax, you are in the right place for help on a problem with your car