rpms running high on highway on 2006 Dodge Ram 1500

for starters my engine light is on,but if I drive on the highway for 15 or more minutes my rpms will randomly jump to 2100 rpms and hold for a second or two then go back down and will repeat every couple minutes until I get back down to city speed limit.

Asked by for the 2006 Dodge Ram 1500
Scan transmission module!... Reply for more info...