05 Chevy Aveo coolant boiling, hold light etc

I have a 2005 Chevy Aveo here . So far we changed
the thermostat , valve cover gasket , alternator ...
have done both oil change and coolant flush . Car
is still boiling the coolant and spitting out thru the
overflow , car gets very hot but doesn't show on
the guage (possibly misreading?) and of course
this leads to the fan not kicking in . Strong smell of
coolant , not showing in the oil either but there's a
hint of the smell . We've also checked to see if it's
air locked . Any suggestions ?!?!?! SOS !