hey besides the head gasket going out...what other problems do the mk3 usually have....like do anything else usually need to be replaced cuz im bout to replace the head gasket and while i got everything off i was going to replace anything that needs to be replaced

just get a toyota head gasket set and you should be good to go. Use new head bolts as well aka ARP head bolts

While the head's off I would go ahead and replace the valve stem seals, the injector O-rings (both sides), ALL coolant hoses and any hard to reach vacuum hoses.