I'm having a very hard time getting the air out of my coolant system. Well at least I hope that's the problem. I had similar problems with my 05 Coupe that has the VQ de 3.5, but I found that it had a bleed valve that helped tremendously. I looked in a similar location, and I do not see one on this HR motor. Does it have one? Somewhere?

 

This image is from the shop manual. Looks like there are two air relief plugs (radiator and heater hose).
Good luck.