Volkswagen Repair: 1999 bug wont change gears, transmission oil cooler, volkswagon bug

Question
1999 volkswagon bug,car will not change gears.It is an automatic,but will not go any faster than 40 to 45 mph.It has been taken to place where purchased,they have changed sensers,wire harness.They do not seem to be able to fix problem.please help if you can,thank you!

Answer
Jeff, thank you for your question.  A couple of things I can think of that might be causing this problem.  One is the bands in the transmission may be loose.  The transmission filter could be clogged.  Something else is low fluid level and a clog in the radiator.  Typically when there is a problem with the transmission, there is a fault code given off by the on board computer.  The computer will tell (with the use of a diagnostic analyzer) what component is at fault or at least where to start.  Usually installing an external transmission oil cooler will prevent heat, since heat is the number one killer of transmission. Another problem can be the pump in the transmission will cause poor performance.  And the Catalytic converter can also cause this problem.
Hope this helps