just joined the forums, I've combed through the search and can't find what I'm looking for. I recently purchased a 2001 Tahoe 5.3 for my birthday. got it for 1700 with 140,000 miles. got it running. previous owner tried to replace intake manifold gaskets and had a hard time. now my issue is it will randomly jump over 210 to the 3/4 mark. I immediately turn the heat on and it will make its way back down to operating temp. I changed the water pump, thermostat and surge tank cap. bled the system the best I know how. suggestions on that would be great. still having the same issue randomly. took it today to pick up my kids and it stayed pegged right below the 210 mark. then later I did an oil change and drove it around after and it did it again. I'm at a loss. if there is somewhere that covers this in the forum that I didn't find please let me know. otherwise any input would be great. all hoses get hot. water pump is flowing good. could there still be and air pocket in the system????