2004 Jeep Grand Cherokee

I have a 2004 Jeep Grand Cherokee that is well taken care of. I change the oil every 5,000 miles but recently my oil light came on. I checked the oil level and its fine. It is also running very cold. it usually runs around 210 degrees but its barely even moving over 100 now and the really weird thing is if i let it set and idle it will warm up to normal but then when i start driving it cools back down to right above 100 no matter how long i drive. I have no idea what is going on so if anyone could help…. thanks