1995 Silverado Ex cab 4x4 automatic

[volusia1]

I have a 1995 Silverado that went into limp mode for about 10 minutes then cleared right up. A few days later it went back to limp mode.

Pull the codes 12 22 66 67 81 82 83.

I know that 22 is TPS 66 is AC 67 is AC 82 is crankshaft position sensor.

What is 81 and 83 How do I take care of the problem of going into limp mode.

I have changed the trans fluid and filter.

Any help will be greatly appreciated.

Thanks