Take it in. My 05 gxp has had 3 trans's put in it. Every time I needed a new one the temp would go up over 210. On number 3 now and it stays around 180-190. Torque converter may be failing as well. Are you getting any slippage. I want to put a external cooler in but GM keeps giving me new(rebuilt) ones with no cost to me. Also, the last two I have babied and they still went. Anyway good luck.