I think the 160f t-stat is too low and it may not be allowing emough coolant residence time in the radiator for proper cooling. Try going back to the stock t-stat.
Thumbs up on the 3 core rad too, i just installed 1 about a month ago, working really well in the south eastern 100f heat. $130 with lifetime warranty for a brand new (not reconditioned) rad from advance auto parts.