kissfan79 - re drain back issue. It's a not uncommon issue with automatic transmisions or DCJ, I experienced it as far back as a generation 1 Plymouth minivan. In general the cause is over a period of time, usually about 8 hrs, fluid drains out of the transmission body passages and partially out of the torque convertor into the transmission pan so when the vehicle is started and the transmission placed in gear it takes a noticable period of time for the tranny system to pump enough fluid for the tranny to function properly. Most systems have some sort of check valve to prevent this from happening. In the 5-45RFE transmission that check valve is apparently in 1, don't ask me which, of the 2 internal transmission filters. Early in KJ production there was apparently a bad batch of OEM filters, hence lots of drain back problems, and some of those filters are still out there for cheap on eBay.
Solutions, assuming you have drain back and not just low fluid:
1. live with it - I did for like 20K miles before having my SunCoast TC and Transgo kit installed. It's harmless but you do have to remember after the vehicle sits a while to crank it up; shift into neutral; hold idle at about 1500 for 10-15 seconds before driving off. 99%+ of the time that works but if when driving off the tranny doesn't immediately engage (NOTE I never really had the problem in reverse only drive) be sure to pop it into neutral and idle a bit longer. If you don't do this cycle you may drive about 100' get a horribly rough engine stall which may or may not throw a CEL. The CEL goes away after about 5-10 good starts.
2. replace the filters being sure they are seated properly.
3. maybe install a tranny cooler return line check valve per viewtopic.php?f=98&t=55110