Reread your post when it gets over 80 c starts stalling ,when it acted up I could barely accelerate I had exactly that problem with a 300 ce turnout to be the eha , whats happening is when running in open loop its ok once it gets to closed loop or warmed up its supposed to adjust mixture via feed back throttle position o2 sensors temp sensors etc , with my 300ce the eha( electrohydraulic actuator) wasent working properly, causing lean condition it can be tested, test 02 first if old to make sure its working