transmission problem

I was leaving for work this morning and when I started my truck up it started out in a higher gear. Im not sure what gear but i know as i pulled out it ran about 2500 rpm for a very slow take off. I turned around to come back home and manually shifted into 2 and even first and the transmission...

I have a 2006 Dodge Ram 1500 SLT 4X4. It has 124,000 miles on the automatic transmission. Recently when driving in 2 wheel drive "D", it shifted fine through the first two gears. I started into third gear and the RPM's jumped to 6,000 rpm and appeared to be in first gear when it got that...