I have a 2007 Dodge Ram 5.7 Hemi Thunder Road 31,700 miles.... Love the truck but am having troubles with it shutting off. I start the truck and it idles up to about 15,000 rpms drops back between 5-7000 rpms thens shuts off. It did it when it was warm out and cold out..Left me sit one night and had to have it towed in, they checked it out and told me computer said missed fired cylinder. They could not find anything and told me it probally was moisture in the fuel....and they reset the computer....well that was when it was like 15 degrees. It warmed up and it still does it , not all the time but every day and several times some days.I have an appoinment tommorow to check the fuel pump but am curious what you guys might think it is? Old timer that worked on Dodges all his life says the back side of the throttle body might be dirty?

 

I think you mean 1,500rpms and then 500-700rpms. These engines don't rev like motorcycles!
It sounds like you are having an issue with you anti-theft. I would see if your dealer can reflash your computer and see if it goes away. If not, have them reprogram your keys or issue you new ones. If the key's signal cannot be read by the module the truck will start, run for 2-3seconds and then shut-off. Also, if you have other sentry type program keys on your key ring, try removing them.