Sorry if I missed it, I haven't seen your problem with heat. Have you checked the 4 solder points on the temperature air control slider?Replaced my washer diverter valve and it didn't fix anything. When I hit the rear washer it comes out the front at about half pressure. When I hit the front it comes out the front full pressure. Pretty sure I hooked it up right..
Also flushed my heater core then let CLR sit in it for about 30 mins. Got nothing out of it. Everything was clean and clear. I'm leaning more toward my water pump or thermostat as the source of my heat problems. It's so weird because the operating temp stays dead nuts between 186 and 195 so I had kinda ruled that out early on but maybe it's flowing enough to keep the engine cool but not flowing enough through the heater. I pulled most of the dash apart again and checked all the flappers and linkages and they all seem to be doing exactly what they are supposed to per the FSM. I'm really batting 1000 on this truck lately... Guess I'm driving the Audi again for a few days till I get parts. At least it has heated seats and good heat.
The only thing I successfully fixed was I replaced the fusible link and junction block. Some jackleg had bypassed it before I bought the truck with a normal wire.