2000 Ram Van 3.9L Tranny problem

[chickyricky]

My 2000 ram van 3.9L transmission shifts horribly when cold but after it warms up it shifts fine. Its been doing this for over 1 year now and I changed the filter and it still does it. When I changed the filter I didn't notice any metal shavings on the magnet in the pan and oil looked fine.
The only other problem that I am having is my ODBll light sometimes come on and stays on for a while then it goes out. Autozone hooked up their little gadget on told me that it is an airflow problem and the engine is running lean. He said it might be a vacuum leak. Could this be what is causing my trans problem??? May be the computer is getting a bad signal causing my trans to not shift right when its cold. Also sometimes when I am idling at a stop light the van dies and it sounds like the trans tryed to shift or something causing it to die. It restarts fine.
The van has 120000 miles on it and is in great shape otherwise.
The Transmission is a 3 speed automatic.

Your help is appreciated,
Ricky Newman