High EGT?

My 2007 C13 is reading high EGTs. It seems to only do it in 10th gear above 65 mph. Relatively flat land. No major hills but it definitely is worse when going uphill.

My air filter restriction gauge barely moves and boost is in the 30's. I think the gauge might be haywire it is reading 600 now and I am idling and been parked 2 hours. It gets to 12-1300 and would probably go higher than that if I didn't back out of it. I was on I-10 and it was doing this and staying up in the 12-13 range so I pulled over and popped the hood. Nothing seemed unusual and when I got back in the cab it was jumping back and forth about 100 degrees. Got back on the road and it seemed to do better. I was able to set the cruise at 78mph and it stayed below 1000.

 

I was only grossing around 50k and it's pretty flat and the speed limit is 80. Last night about 10pm I was doing 78 and rolled up on a diesel bear doing maybe 50 and blew around him like he wasn't even moving. I just knew he was going to pull me over but he didn't.

 

Truck is new to me. I drove it from Missouri to Texas bobtail and it it ran fine but this is the first week pulling anything with it. I assume it is a stick tune but do t know for sure