Hey everybody new member here. I have a 2015 Laramie longhorn ecodiesel. I'm having an issue with my heat. I recently had a leaking water pump and I replaced it at about 104k. Truck has 117 now. Every since then, my heat hasn't been working while driving. It works like a champ at idle but as soon as I start driving and I get at a steady speed, the heat goes out and just blows cold air. I've drained and burped the system twice, both times to no avail. First time I was trouble shooting the leak, I put water in the tank to find where it was leaking. I sucked it all out with a shop vac to remove all water. Maybe not the best idea but idk. Anyways, I know how hard it is to get the ecodiesel up to the temperature in order for the thermostat to open to burp. So I drilled a small hole in it to let coolant pass through so air would escape. Even before that, when filling the coolant tank, I left the nipple on the top of the thermostat open untill coolant came out. I highly doubt there's an air bubble in the system since the heat works part of the time and not under load. Could it possibly be the heater control valve messed up? I heard when it screws up you get a CEL? Could I have also messed it up by sucking coolant out with a vacuum? Help needed asap since it's starting to get cold here in Louisiana.