lumpy idle at 900rpm

Hello, I've got a 2012 780 with the D13, for about 3 months now I've had a strange idle problem at just 900rpm. 850 it's pretty smooth, 950 its pretty smooth. It's been to the dealership several times for this issue, they have replaced all the injectors and cups, turbo, preformed a compression and engine balance test, with no luck, but here is the kicker, it only does it when the engine is hot, when I fire it up on the morning it's fine, the hotter it gets the worse the viberation, feels like something is out of balance I can even hear the viberation in the engine through the intake sound. Volvo did find some air bubbles in the fuel and replaced a fitting on the front of the head and it did seem to help on a cold engine since before it vibrated hot and cold, but now it seems to do it once up to operating temp or hotter. Also I've noticed the truck has been running alot hotter then usual, always seems to be at 210, even idling with the hood open for 20 min sometimes it stays running hot, used a temp gun on the engine and all temps seem consistant. Also noticed that the cooling system seems to be running at a higher pressure then I could remember it running at. It's been pushing some coolant through the cap a little bit, but always running not maybe that happens? But anyway any ideas would be appreciated.

 

It was the fuel fitting on the front of the head, engine has 770,000kms on it, the dash bounces up and down, when I look at the transmission and or put my hand on it by the rear it's an up and down kinda shake, it has an ishift. The idle is stable and it's like a doum doum noise, valves were set when the injectors were replaced. None of the repairs except the fuel fitting made any kinda difference, but all the fitting did was soften it when it's cold.

 

And it seems to be holding at the the same intensity, a few times very few times the viberation has gone away for a split second then returned.

 

Yeah the viberation feels the same when it's pumping or not, engine seems to have decent power, I wouldn't say it's lacking power or boost.

 

That is possible, prior to the viberation. Well I'm pretty sure it didn't before, but my EGR cooler had a really bad leak, truck was drinking close to a gallon a day worth of coolant . For probably close to a month, but I got that fixed along side the transmission was replaced. They also replaced the dpf.
The oil sample was high in sodium and potassium, as well as Tin. But samples are normal now.it's just strange it's only lumpy at 900rpm.