Trans shifting

[sledhaus]

I have a 94 Chev 1 ton dually 454 4x4 at work with an automatic (700 I am guessing) that has been working just fine with some medium duty towing and mostly light road trips. A few weeks ago the boss went on a local run and it wouldn't shift out of second gear in forward flight but reverse worked fine. After it sat for a while it shifted fine again. The second time it happened he took it to the trans shop and they said it had metal in the pan and insisted on an overhaul. $2500 later it drove home from the trans shop just fine then last night on a local run it wouldn't shift out of second gear again. We stopped a couple times and let it sit a few minutes but still second gear only even when starting in first gear position. Then after idling for half an hour while we loaded a trailer it shifted fine all the way home. Exactly what it did before the overhaul. Could this simply be a computer glitch or is there a module that controls shifting. The trans shop said bring it back of course but they obviously don't know what's wrong.

[lagrange151]

Second gear is the "limp in" mode gear, could be a computer issue.