When it is cold outside my dakota wont shift into gear until I let it sit and warm up for about half hour or more. After warmed up it drives good. It doesn't do this until temp gets around freezing.

 

check your tranny level and if its not low flush and a new filter asap or you wont have a tranny

 

sounds like low fluid to me, could also just be the cold weather, freezing temps thicken trans fluid which obviously leads to poor circulation in the tranny, let it warm in neutral and see if that helps.
It's obviously your perogative but from my experience, all of the trans I've seen that have not been PM'd (preventative Maintenance) on a regular basis don't do well after being PM'd when the first sign of potential issues arise. If the trans is getting it's first PM at over 100k, the PM will not help you. I've seen hundreds of trans go south b/c the owner wanted his trans flushed/filter changed at 120-140k. I tell people that if the trans has not been PM regularly, starting now is not going to help, it actually worsens any condition the trans may have. When I was younger, 2 of my trans were beginningto shift awkwardly and after the flush and filter on both of them I only got another 100-110 miles from them.
My dad's truck is nearing 200k w/o a PM on the trans, and his last two trucks had 250k before being traded for new ones, I don't know, but to me 200-250k out of an untouched trans is awesome and who knows how many more miles his other trucks would've had if he kept them.

 

I agree. I'll clarify the reasoning for letting it warm in neutral: these transmissions don't pump the fluid in park.


That's what I've heard too. I've had/seen a few transmissions that have been PM'd late for the first time (over 100K)without any new problems popping up, but it didn't get rid of the existing problems.
As with anything else, proper and timely maintenance is important, and not doing that can lead to problems in the future. It's very easy to inherit other peoples bad maintenance (or, just no maintenance)in a older vehicle.