110 Deg. is still on the high end of "Normal"
The fact that you can put the ACC on full Heat to drop the engine temperatue down 10 to 20 Deg. doesn't really indicate anything - I would expect that to happen.

I still think you need to check the Thermostat and do the 'Top Hose Test' for a possible combustion leak. Take the Thermostat out and see if it makes much difference. If you aren't sure how long it has been there just buy a new one and replace it (along with the seal of course). They aren't that expensive.

My SDL runs in the 80-90 Deg. range with the A/C on and can rise to about 95-105 Deg. on a really hot day in slow traffic.