Well I searched the other day and the heater core is not directional. I did decide to switch the heater hoses to see if it would unclog the core by pushing the crud the opposite way. It kinda worked I guess. I'm not getting alot of pressure buildup. But it won't stay hot either. It gets warm at idle, rev it to around 2k and it gets hot. Then let it idle again and goes back to warm.

Took it for a short ride and when moving at a decent speed it steadily goes back to cold again, like the tstats stuck open. I haven't pulled it out yet to see but that's my guess. It got down to like 15 degrees here yesterday. It's way too cold for this.