My 2007 Dodge Ram 4.7 liter has 86,000 miles and lately has been going 1/4 past the middle mark on the gage. The truck sometimes also while a/c is on and in park position accelerates and decelerates up and down. What is the problem?

Depending on ambient temperatures, you may see slightly higher coolant temps. This doesn't mean that it's overheating.
What is the maintenance history for that vehicle's cooling system?
If you haven't serviced it lately, now may be the time for a fluid exchange and a fresh thermostat.
Regarding the fluctuation in engine speed while the A/C is running... that is normal. As the A/C cycles on and off, the PCM adjusts engine idle to compensate for changing loads.

This link should help:

https://www.askmehelpdesk.com/cars-t...tml#post235973