we have a 2000 f550 w/7.3 liter turob diesel .The problem is at highway speed 60mph,the truck is loosing power. lots of blue smoke,checked codes speed sensor error replaced sensor, fuel filter, air filter ,trans filter, and fluid .The engine starts fine runs well at 40 mph . Also overdrive light is flashing at highway speed.

 

Check the converter

 

Blue smoke? compresion check??

 

Any Codes?