HELP! 14.0 Liter Detroit using oil (EGR)

I have a 14.0 Liter Detroit (EGR) in my 2004 Freightliner Columbia. It is using as much oil as I use water for a shower. I haven't had to add any coolant, no oil in the diesel, I have drained the air tanks and no signs of oil. However, the sensor that is under the fuel pump (behind the air compressor) is oil soaked, eventhough I just changed it last month. Going down the road doesnt show any indication of oil from the exhaust either but after idling for a while and then taking off it smokes like hell then clears up. It has been burning oil over the past two months and the blowby doesn't seem to be anymore than when I bought it. It has 817,000 Miles, and I just purchased it in March of this year (2010). It had..... 770,000 on the odometer when I bought it and no oil consumption issues at all. It does have the inherent Detroit backfire issue around 1300 RPM and sometimes will do it more than once under load resembling a constant pop and it doesnt do it multiple times all the time but it will stumble everyday though. Since I've had it I have had to replace the Air to Air due to a crack on the passsenger side. I didnt see any signs of the turbo leaking when I replaced the air to air, which I replaced myself (I'm a mechanic but a Diesel engine parts replacer.. lol). It also seems like the EGR sounds from the engine have changed, so I'm not sure if the EGR could be dumping oil into the engine or bad?????? Does oil even run through the EGR valve????? When high up in RPM's (above 1500) it sorta sounds like it is rattling, resembling a light rod knock or something.
When idling it starts smoking after a while and worsens after extended idle then will clear up then will worsen again but never fully stops smoking. Oil pressure at idle appears to be 27psi and off idle close to 50 psi but sometimes it appears to be around 40 going down the road last week it was 3/4 the way between 25 & 50 PSI. I remember when I first got the truck and I idled , you would hear the EGR function working intermittently because I like the Jet engine like spooling noise it makes but now I don't hear it anymore. I have added 6 Gallons on a 1300 mile run because the engine protect light came on due to the oil level being critically low. I added 3 Gallons the other day in Arkansas and after delivering and driving back home in Louisiana it looks like it needs about 3 gallons. I am pretty sure it could be time for an inframe but wondering if it could be something less major, like valve guides being worn or something and I can replace the head or something.
I dont have any maint. reports on this truck as I bought it used from a large volume truck dealer in Texas. Basically, what I need to know is what steps do I need to take in order to diagnose this problem? I really need someones expert opinion and diagnosis. I like the truck but getting frustrated from the sudden HUGE oil consumption issue.
Everyone is quick to say inframe but I've heard of HUGE oil consumption issues and it turned out to be a oil cooler, Egr valve or something that wasn't major. I live in Baton Rouge, Louisiana and DON'T... I REPEAT DON't want to take it to Capitol Freightliner because they never seem to fix anything! and they said "Oh, it's time for an inframe......" I guess so for $18,000. Finding repair facilities to me are just dragging my spirits down because everyone seems to be guessing. I want to KNOW what it is and then go from there only after it being diagnosed expertly and not on a expert guess. Sorry for the lengthy post but I'm trying to paint the best picture that I can.

 

Ok, The guy from the shop just called me concerning my truck. They put a meter on it and drove it down the road and said that I had 9inches of base pressure andthe max is 3 inches. He's saying that more than likely its a piston/liner. That means Inframe time.

 

No nothing sprayed on the underside. It's just using alot of oil and when you remove the breather tube you can see that, in my opinion that a cylinder or two is bad (cracked ring or something). I just feel that If I pull the head then I can go ahead and do an inframe. He quoted me $10,695.00 for a level 1 inframe which includes another head, oil, gaskets, bottom end bearings, and a 1 Year warranty that is good at any Detroit Diesel Shop worldwide.

 

Went over by the shop today.... Shop did a leak down test and found cylinders #2 & #3 were not holding well. Upon techs inspection he heard air seeping into the crankcase from #2 hole and also #3 hole but not as bad... Pulled the head and found #3 to be scored heavily and grooved. He's thinking broken ring or something but won't kow until he pulls the pistons tommorrow. Now, they're having a hard time finding the OH kit because I have a DDEC 4 (EGR) engine and the rest were DDEC 5 (EGR). Stewart and Stevenson doesn't have the kit and they are contacting all of their supply warehouses but havent found a kit yet. They've even contacted Freightliner..... go figure.....