Well first off I would say hit up the PNP and snag a factory electric fan, just for s and giggles and see if it helps with that begin the only change made.. If so, then one I would def take the other one back just to get that money back.. and two I would try and have your compression checked for each cylinder.. I would say flush your complete coolant system too, including the heater core.. When I did the water pump on mine, the coolant passages that I could see behind the water pump had all kinds of gunk in them, so I put the hose in there and flushed as much as I could out that way, then I flushed and back flushed my heater core quite a few times and between doing that stuff it def helped get my heat level back down some on my 98.. But being as how you have the 00-01 problem child years as far as the heads, I know you said there was no look of mixing between coolant and oil, but never hurts to get that checked anyways as far as the compression, especially the rear cylinders... I had a friend who had somethign similar going on with his 01, and was just about to junk it save the money he had already spent on it trying to figure out the issue, and after doing a compression check one late night after I got off work and drove to his place... we found that both rear cylinders were fairly low, so we pulled the head and found out that the head gasket between the rear cylinders was shot, so it was allowing coolant to drop onto the top of the pistons and was being burned off, and was causing the coolant to stay even warmer then usual due to the obvious higher amount of heat coming straight to it from the combustion chamber.. so figure it's worth a try, and shouldn't cost too much if you don't have the tool to do it yourself.. You can also pick up a tool from Harbor Freight or even rent it @ AZ or another auto parts store...