This is going to be a long post...
Don't confuse the EGR VALVE with the EGR COOLER. The valve opens and closes to regulate the exhaust gases that are allowed to re-enter the engine (for pollution control purposes). The EGR cooler does as its name implies, it cools the exhaust gases before they are sent back in to the engine.
2 months ago would have been the optimal time to address the oil cooler/egr cooler failures, when you had it all apart. The oil cooler plugging could very well be the reason your head gaskets popped in the first place.
Here is what I would do in your situation:
First: Stop driving the truck, unless you want to redo your head gaskets again.
Purchase a new oil cooler and egr cooler (if you so choose or need to keep your egr system intact).
and download a copy of "nylyons' reverse flushing technique"
Read over what it takes to properly flush the cooling system of a 6.0, but disregard any and all mention of reverse flushing
. The reverse flush will not
help you in your situation whatsoever. This step will remove all the junk that clogged your existing oil cooler previous to undertaking your repair. This styke of flush will not be done by any garage or mechanic out there. The reason is simple. The time involved would require that you pay him for 8-10 hours to flush your cooling system. You would get the bill and faint, and he has much better things to do than to flush your engine/cooling system.
You will need to do a few things to prepare your engine to perform the flush as safe as possible. (By the way, the flushing will take you the better part of a full day to accomplish).
The first is to perform a mod that will raise the idle speed of your engine to 1200RPM so that the chemicals you need to use can circulate throughout the cooling system/engine.
Luckily you have a 2006 and this modification is exceptionally easy to do (someone will let us know whether or not this works on a manual transmission, as I am not sure of that).
Tucked up right above the emergency brake pedal is a bundle of wires that have black shrinkwrap on the ends of them. In that bundle, find the purple wire with a green stripe. All you have to do is get 12 volts (switched/fused at 5-10 amps) to that wire.
There are safety locks that must be in place for the idle to jump to 1200 RPM. Those are:
The emergency brake is on
The regular brake is not applied
The transmission is in Park..for auto trans models. I am hoping that the standard trans being in neutral would also work. If anyone reads this and has a standard trans that has the high-idle mod done, please post what had to be done if anything is different.
The second thing that you have to do to be able to run the engine for the flush is to prevent the leaking coolant from entering the engine. There are a couple ways to do this. One is to remove the EGR valve and verify that it is closed. Reinstall the egr valve back in to the intake manifold and do not connect it electrically...and pray that it will be ok.
Warning: DO NOT
think that you can drive the truck with the egr valve unplugged electrically and everything will be ok. It won't be. The boost pressures from the turbo can force the valve open. With the engine running in this manner, a large amount of coolant can be waiting behind the valve, and if the turbo forces the valve open, your looking at yet another set of head gaskets. Don't do it.
If you saved your old egr valve, tack weld it shut and install that back in to the intake.
Again, don't think you can drive the truck around much with the egr valve welded shut. There are other ways that a leaking egr cooler can have a detrimental effect without going past the valve. The leaking coolant still has to go somewhere, and that somewhere is out the tailpipe. Before it can exit the tailpipe, it goes through your turbo. The soot in there, along with coolant can make the unison ring (that controls the vanes that make boost) stick, causing an underboost or an overboost condition.
If you have a Catalytic converter under your truck, coolant going through that can cause it to plug up prematurely also.
Once you get all the above done, its time to replace the oil cooler and egr coolers.
to go to a "sticky" on this forum that has the pdf files you need to do this, as well as some parts that you should consider updating while they are already off the truck and in your hand. It also has some tips/tricks posted as well.
Good luck and happy wrenching