||I've got a 6.5td and 4L80E on my dually, it resets when the key os turned off. If the error returns it will go back into limp mode depending upon what the error is. You need to have it scanned to get the error codes, then you can fix it with the right parts. Otherwise your tossing parts at it without knowing what's actually wrong. The 4L80E has 1 VSS sensor, 1 input shaft speed sensor, 1 output shaft speed sensor and a host of other solinoids. If one of the input or output speed sensors goes bad, it thinks the tranny is slipping or not in the right gear and poof limp mode. The VSS is not the only sensor that causes what your describing.
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