Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice, so feel free to add any additional info at any time.
With me not being there it really limits my capability’s on a problem like this. Seeing that it was just rebuilt and they didn’t spot a problem makes it pretty safe to assume the problem is not mechanical, since they went through the whole transmission rebuilding it. I really hate to guess when it comes to problems, but not being there it's all I have to offer, consider it trying to point you in the right direction. All that being said, I have seen this set of symptoms I believe 4 times in the past. Just neutral all at once for no apparent reason with a E4OD transmission. One of them had a broken wire in the harness and it was a nightmare to find. The conductor was broken inside the plastic, and looked fine from the outside. It made contact most of the time, but would intermittently loose contact, and trigger the transmission into neutral, it took over 50 hours of searching to find this one, if I remember correctly, a real nightmare.
The others had problems with the transmission range position sensor. It's known as MLPS, and it is on the drivers side of the transmission case. If the MLPS tells the electronics that the shifter is in the neutral position, the transmission goes into neutral. The early types of MLPS units were variable resistors, and did suffer from mechanical wear. When they get worn, they get flaky. There is no way to test for this in most cases, and no way for me to be sure it is your problem. I would double check the number, I pulled one of the files on one of these trucks, and it was a Ford part number F5TZ-7A247-B it's the MLPS. The same number ending with an A is the first version, the number ending with a B is an improved part. Remember double check this number for your exact model. I know how frustrating this type of problem can be, I hope this helps. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
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