I'm having some trans overheat issues that I hope you guys can help me with. Truck runs and shifts great for about an hour of driving then begins to overheat and If I were to continue driving I get the 'trans fault' message. Drained the fluid in the pan and added fresh fluid 3 times and replaced the filter twice. I've already removed the external "thermostat" block because the lines had rusted out. I also cleaned and blew out the cooler so I know there is no blockage there. One thing I noticed is that when I ran the truck with the cooler disconnected to help exchange the fluid I get almost no fluid flow from the trans mission and shifting into gear or increasing RPMS don't have any effect. Seems to me like there is a blockage internally somewhere restricting fluid flow to the cooler. Are there any other internal filters or screens that may be blocked? any other ideas?