06 jetta tdi p0746 problems

I have a 06 jetta tdi automatic. Recently did a cam replacement. 350 miles later while driving down highway, lost power and gear indicator gauge starts flashing. Car won't shift out of first gear until it cools down. Now every time it gets to normal operating temp, it acts up. Gauge flashes and 1st gear. Any ideas? New to the whole VW scene.