I have a 2003 Acura TLS, bought new Oct 2002 currently with only 42600 KM (real low) My problem appears to be the same. I noticed specificly on warm days after 30 min driving, when coming to a stop, the idle was about 3500 RPM. Parked the car, turned it off. When starting up again, RPM stayed at 3200, also couldn't put into drive (possibly safety mechanism to prevent damage to transmission). After 30 min when cooled, was able to start again - OK.
I brought it to the dealer thinking possibly connected to FAULTY TRANSMISSION". There was a special extended warranty issued by ACURA >>> http://www.internetautoguide.com/auto-recalls/09-int/2003/acura/tl/index.html
I believe it also includes 2002's. Your Dealer should check into it again.
My dealer, ACURA LAVAL (in Que, Canada) seemed to look at nothing else than the transmission. In fact, 2 days after not hearing from him, he told me that they had already ordered a NEW Transmission which is being put in as I write.
Hope this is helpful to any Owner/Dealer who reads this
Best Wishes from the Great White North- Canada