Hi Steve-
I've been playing with the same problem with my AD for awhile too
I don't get up to 230 but anything over 200 bothers me.
Since your heating up in traffic and cooling down going down the highway I'm thinking you have a lack of air flow at idle but with two fan's going I can't see that being the problem. Now at higher rpm your also spinning the water pump faster and moving more water so that could also help the cooling. Do you have any type of high flow thermostat or water pump installed? I added a Stewart high stage II pump unit to my small block and knocked down the temps close to 10 degree's. It also takes longer for the fan to finally kick on so I know the pump has helped. Are you running a distributor with Vacuum advance?
