So.. I'm a mechanic and I bought this 2005 LR3 4.4 V8 knowing that had an overheating issue... I fixed the leaks, put a new water pump, got the radiator fixed (had a little pin hole, nothing bad) replaced some hoses that looked old and non trusty, put new thermostat with the whole housing, flushed the entire system with a water jet, air lifted the system to make sure there was no air pockets. and still overheated on me. Performed a hydrocarbons test to see if there was a head gasket leaking but came out negative and I did it about 5 different times. I tried a new reservoir cap and that seemed to take care of the issue for about an entire week. I parked the vehicle and I didn't use it for another week until now and it overheated again. Before it was blowing hot air out of the vents on full blast but now nothing. Any ideas?