I have a 2011 f350 with the 6.2l gas. The problem I am having is the truck blows cold air at an idle. I installed a greaser in the back that you tap into the heater hoses to circulate hot water thru to keep the grease flowing in the cold temps. If I rev the engine up just a little i.e. 1000rpm or so, It has nice hot air. I have bled this and really run the heck out of it trying to make sure its not air bound. There is a restricter in one of the heater hoses from the factory. Im wondering if I should pull this out? any thoughts on this problem?