If it is indeed an e4od, the converter locks electronically, by grounding out the circuit. However, low fluid could probably cause the same thing, but at an inconsistent interval like you are experiencing. Unfortunately I don't know much more about them, so maybe someone who does will chime in...
i puked it pretty good, somewhere in the neighborhood of six or seven qts by my guess. It seems to have just about gone away driving it last couple days as i have brought level up to spec. Hoping someone will pop in that has had a similar experience also hope i didnt hurt anything and the symptoms are just a product of the extreme low fluid level.
I think its an E4OD but thats from searching on line i wouldnt know from lookin at it . . .