Just another little footnote on this topic.
Regardless if you go for another engine, or repair the one you have, you will either be re-using or transferring your misc. parts.
Because of the meltdown you've described, I would have a very good look to see if there is a problem with the # 3 injector or intake gasket.
I'm saying this, because I suspect you may have had a very lean condition on that cylinder.