Hello I have a 1987 f250 diesel with c6 3 speed transmission. It has developed a shudder when the outside temperature is above 90 degrees. When temps are cool, it doesn't seem to shudder. I recently changed transmission fluid and drained torque converter, filter, and cleaned oil cooler with no improvement. The band has been properly adjusted as well. Shudder begins when accelerating from a stop up to 35 mph then seems to go away. It also occurs in reverse gear. This is also a non-lockup converter. Any help would be greatly appreciated thanks.