i hear you I spoke w/ Guru Bob White and just went over your situation; possiblities:
reduced air flow through your coolers up front, an issue w/ the trans causing overheat; unfresh fluid but I know you already did that; when you first start up the truck is it reporting accurately? for example stone cold ambien temperature 80degress on start up is your TOT reporting correctly?
restrictions in your cooler system, may need to install another cooler "parallel" (not in series); here are some items we can try; first gerneator or heat is torque converter as it spins, that natural slip and then second cooler flow system, you elminated the pellet design now you have full flow w/ stl010; gotta research deeper, 200+ is high, averaging on a healthy unit 155-165F unless stop and go traffic or situation.