voodoo

Sorry, been a long time since 90-94. Should be easy enough to check flow by cutting the heater core out of the loop by disconnecting the hoses at the heater core nibs at firewall and tying them together to complete the coolant circuit. Clogged heater core would create the same symptoms.

Probably just your heater control valve not opening completely. The extra revs give the water pump a boost and push hot water past the valve. Also will cause a perfectly good head gasket to pass an occaisonal air bubble from the hydraulic back pressure you're building up. All gaskets leak - it's just a question of whether or not it is an acceptable quantity.

found nice 98/99 outback with blown 2.5 (compression in radiator). I've got a good early 90's 2.2 out of an obd1 wagon. is it worth the time to swap and are the 2.5's junk if it's just a head gasket? anyone know if they are prone to cracked heads or not. thanks voodoo (orphan in an earlier incarnation )

Yep, too bad: one vise with a 4" throat and one 4penny nail does the trick. BTW, one of my 91 Legacy's has just over 600k on the old style tensioner - they either compress and decompress or they fail in the vise. Remember to wrench the engine over at least two full revolutions to set the tensioner to full extension. Good luck, voodoo