98 Subaru over heating issue?

What is your question?

My 98 Subaru Legacy outback overheats when driving for 30 minutes, have flushed coolant countless times and replaced the thermostat also replaced sensor spark plugs checked heater core and fans are working, replaced waterpump, the upper radiator hose seems to be under a lot of pressure and is starting to bulge. And coolant backs up in to the overflow reservoir. I also have don't a block test several time and it's come back all clear. I have none of the symptoms leading towards it a head gasket.

What makes this problem better or worse?

Nothing

How long has your 1998 Subaru Legacy had this problem?

A month or so