At this stage of the game I'm inclined to agree that inappropriate fluid (e.g. not ATF+4) is a potential cause along with possibly bad or somewhat clogged filters so a fluid and filter change is in order. The only way I know of to get all the fluid out is a complete flush and fill but I honestly cannot tell you how to do a flush (e.g. complete fluid change) on the transmission. Hopefully someone knows. Alternatively, I know it's a pain in the you know what absent a tranny pan drain plug, you could consider several fills and drains before doing the tranny filter service to get most of whatever fluid is in there out.

In theory you can do a complete flush by disconnecting the tranny to tranny cooler line and using the tranny, presumably in park or neutral (there is a suggestion that this tranny pumps fluid faster in neutral than park), pump fluid out of that line into a bucket while pouring new fluid in as fast as it pumps out. How safe or effective that process is I have less than zero opinion.

Anyone???

At this stage of the game I'm inclined to agree that inappropriate fluid (e.g. not ATF+4) is a potential cause along with possibly bad or somewhat clogged filters so a fluid and filter change is in order. The only way I know of to get all the fluid out is a complete flush and fill but I honestly cannot tell you how to do a flush (e.g. complete fluid change) on the transmission. Hopefully someone knows. Alternatively, I know it's a pain in the you know what absent a tranny pan drain plug, you could consider several fills and drains before doing the tranny filter service to get most of whatever fluid is in there out.

In theory you can do a complete flush by disconnecting the tranny to tranny cooler line and using the tranny, presumably in park or neutral (there is a suggestion that this tranny pumps fluid faster in neutral than park), pump fluid out of that line into a bucket while pouring new fluid in as fast as it pumps out. How safe or effective that process is I have less than zero opinion.

Anyone???

Check the gasket on the pickup filter neck the next time you have it open. Some aftermarket filters do not have one, or a poor excuse for one. This causes air to be sucked through the system and all sorts of erratic behavior with the tranny.

I'd agree that you still have some of the old incorrect fluid in there but IMHO the fact that you engine's cooling system tstat is not bringing the engine upto full operating temp should have little or nothing to do with whether or not the transmission is fully warming up. Easy enough to tell, after a 40 mile drive pull the transmission dip stick and if the end is essentially too hot to hold the tranny fluid is at operating temp.

In the two fluid and filter changes I've done on my CRD I've found that most of the fluid drains out of the system. The manual lists the service fill as 10 pts (5 qts) and the overhaul fill as 28 pts (14 qts). When I drop the pain to drain it I let it sit overnight so everything can stop dripping and I can get a good seal with the RTV. It's one of the jobs I don't like to repeat.

Anyway, both times I've done mine I've gotten about 9.5 qts out. I figure another half quart was in the filters, shop towels, my hands, etc. So I put 9 qts in before driving, get it good and warm, and it's taken another 1 to 1.5 qts to fill it. I was surprised by this at the most recent change so I checked my notes from before, and sure enough...10.5 qts.

So if the listed capacities are correct, then most of the fluid will just flow right out. The easiest approach might be to change it with cheap ATF+4, run for a week, and change again with some nice synthetic ATF+4.

My intention is to do another drain and refill next weekend, by which time I will have the Tstat on hand and can replace that, too.

I'll try to address both point separately:
1. not quite - tranny fluid circulates thru the system, including as far as I know the tranny cooler, whenever the tranny is pumping fluid and the harder it's working the more fluid it moves and the more heat it generates. Trannys rarely pump much if any fluid in park but they do pump in neutral which is why if you suffer from the fluid drain back problem, I do, you can avoid that problem by 10-15 seconds of high idle in neutral before driving off. As long as I can remember folks have been idling the engine in cold weather to "warm" it up with the tranny in park totally ignoring that there has been no need to do this since multi-weight oils were invented AND since there is no connection to speak of between engine temp and tranny fluid temp that doing this meant they were driving on a warm engine and a cold tranny (not good for tranny). Best to crank up, idle for like 15 seconds (ideally in neutral) while you adjust seat/seatbelt/mirror, then drive off at a moderate speed until the temp gauge shows signs of life. That way both engine and tranny/drivetrain are warm. Before someone flames me yes I know we have a 2 stage pump and there may be a bit of fluid pumped while idling in park but if so not much, I know as doing so won't get you past the drain back problem but idling in neutral will. So since there is no particular connection between engine temp and tranny temp and absent a tranny temp gauge the only way I know of to check tranny fluid temp is the old fashioned finger on the dipstick test.

2. ATF+4 may or may not always be synthetic I simply don't know. What I do know is ATF+4 is a tranny fluid spec that must be met for Chrysler transmissions and that http://www.centerforqa.com/licensedatf4brands.html provides a list of fluids that meet that spec. That's a polite way of saying just because ATF+4 is on the bottle doesn't mean it's certified to meet the specs (e.g. it might or might not) so I'd stick with listed products. Similar with antifreeze stick with a name brand that you positively know meets spec and stay the heck away from anything that says "universal" or "compatable with".

I suspect fluid is some if not all of your problem but one other thing to consider is after you have purged the whatever it is stuff you might have to run a "quick learn" procedure on your transmission unfortunately that's requires a trip to the dealer so if things pretty much smooth out drive for a while and let the tranny learn on its own. Others may have more knowledge about this than I do though.