Could it be the engine

I have a 2004 sebring convertible that made a
metal on metal sound drove for a little bit further
then shut off.  I had to get to get out of traffic so I
attempted to start it again, which it did.  It ran a
little shaky got out of traffic but stalled and
wouldnt start.  The antifreeze was boiling and is
now dark.  The oil cap wouldn't come off but did
the next day.  I put oil in it and it started right up
with no noise at all.  Could I have engine trouble or
something quite not so expensive? Help please.  I
really love this car.  I picked it up for $200 because
it had front fender damage.