Before you do anything with the transmission, have the Transmission Range Selector checked. This is a known source of problems for Ford. This is kind of like the old neutral safety switches in the old days, but with a twist. It's a switch with resistors in it. The different resistance values tell the computer which gear you're in. When the switch starts to fail, it gives all kinds of erroneous readings which messes up the computer. The fact that it resets on restart is a very good indication that you're dealing with a switch/sensor problem and not a hard transmission problem. If you have a digital multi-meter, you can check this out yourself. If not, have it checked out by a pro who has heard of this problem before.
If you want to do it yourself, buy a subscription to an online service manual for full instructions. Alldata is $25 for a full year, Mitchell is $10 for a week.
http://www.alldatadiy.com/
http://www.eautorepair.net/