Always nice to hear good feedback! Thanks! Glad you have found the cause of the problem. Just keep track of it for a bit and you should be good!

 

I know the problem is fixed...but here is another way to bleed the lines...in case you ever have to do it again:

(make sure the engine isn't hot when you do this) but leave the rad cap off when the truck is on and rev up the engine using the throttle under the hood. Hold it steady around 2k for a bit, then rev it. Then go to 3k, hold and rev, and just keep cycling like that. The air in the line should start to bubble out of the top of the rad. You will see air bubbles coming out. Make sure to keep doing this long enough so that the thermostat opens. After all the air is out of the main lines (ie. no more bubbling), it might be a good idea to turn the heat in the cabin on full blast too to open up the heater lines to the heater core. Follow the same process again to ensure all air is out of those lines.
Hope that made sense lol. Just good info to have incase you need to do it again.

 

Just a note here. Coolant is always flowing through the heater core hoses. It is only the air in the HVAC system that is not flowing over the heater core when heat is not requested.

It helps greatly to elevate the front of the vehicle and also to have the passenger side front higher than the passenger side front.