Been searching the forums but didn't quite see my exact issue. My 99 Silverado 1500 rwd Will drive just fine in town. If I drive on the highway, it won't shift into od and then seems to lose power and possibly be in limp mode. I have to pull over and shut it off in order to get back on the road. I don't feel any slipping. Speedo works fine but seems slightly erratic, so do the other gauges. No engine light, but it is throwing C-codes
C0281, C0226, C0222, C0265