1999 Dodge Durango Slipping

I just purchased a 1999 didge Durango. When its first ran in the morning and I accelerate it will not shift gears for a few minutes. Example enter freeway Speed is 70 MPH and I will drive for about 1/4 mile and the RPMS are at aboout 4.5 before it shifts. I had to pull off the freeway One morning as it almost cause a collision. Now when it warms up the tran shifts fine. It;s just that first initial start in the morning and for the rest of the day it is fine even after sitting 4 or 5 hours. In my opinion it works fine when everything gets to normal operating tempeture. Now Im sure this is not a normal accurance with this vehicle so is something fixing to go out completly. I have read some articles and so far it all points to a PMC part that is some tiype of computer that has something to do with the Shifting of these transmissions. PLease let me know your opinion Thanks So much. This is my first time on this so I am uncomfortable with any donations. If This is what I beleive it to be I would be glad to donate at a later date. Thanks