mx 13 running rouph... egr problems or what?

sorry for the long winded description but it should answer any comeback questions ahead of time...

i have a 2012 pete 386 with a pacar mx 13 @600k (yah, I know, it's been a year and a half of hell on earth. thanks pacar!) here's the rather long story, looking for answers.
the problem started a few weeks ago wile it was -30c out. i have been having fuel leveling issues every time it dropped below -15c or so but believed it to be a fuel cap issue. one night, after running in a horrendous wind i noticed it seemed to be idling very rough when i stopped. i also notice that the exhaust smelled like... old paint that you just opened after a few years(i only put diesel clean in once a month and hadn't added any recently). the next day, when i fired it up, it started roughly and i got a delta P code along with a #1 particulate filter code. restarted it and the codes were gone. on the way home i stopped for a bite to eat and the codes came on again when i restarted it after about an hour or so(-15c). again i restarted it and the codes diapered. then it ran kinda rough the rest of the way home(kind of rumbley). had an oil change the next day changed the fuel filters, oil filters and air filter as well. went out again and again had the code issues after shutting it down for a while) as well as the rough idling. brought it into pete and had them check it out. they cleaned the egr sensor and replaced the delta P sensor. when i went to pick it up it was pretty cold(-18c) and it seemed to start weird. like it wasn't firing right(chugging). then it smoothed out and seemed to idle great. took it out again the next night and it started idling bad again and this time was running rough up top as well with very grumbley acceleration. i also notice that the DEF fluid seems to be going down a lot faster than normal. on flat stuff it seems to smooth out. the further i drove the worse it seemed to run. then the fuel leveling problem returned. the right side tank was spilling over and the left side(the one with the gauge) was going down fast. i stopped and shut down the left side to try and get it burning off the right side for a wile. i noticed that almost immediately it started to idle better. but when i had gone down the road a few miles the "STOP ENGINE" light came on. i slowed down to stop and it went out. i was only able to run at about 70kmh without causing the light to come on. however it did seem to run smoother. i added some 911 at the next stop and it seemed to have gotten rid of the engine light so i assume the fuel had gelled a bit in the lines(-25c). once the tank had gone down a bit i turned on the other tank and it seemed to be leveling again. however the rough running continues. once it's been idling for a while it smooths out again and seems to be better but after a few miles it starts up again... and gets worse the further you drive. the weird thing is as soon as i drop the loaded trailer and park up it seems to be idling great again. i should mention that the problem is hardly noticeable when dragging an M/T trailer. and non existent when bobbing. I've had no codes since they worked on it(other than the shut down wich was obviously due to fuel restriction)... just poor performance. I've tried to research this and the EGR valve seems to be the culprit that most closely represents my issues: road speed has not been effected, it still reaches top speed(105kmh), but grumbley.
idling rough, poor/rough acceleration, rough starting and decreased fuel mileage.
however given the fuel issues I'm having i don't know if it's a separate issue or if they are related. given the cost of repairs($3,200) I'd like to be a bit more informed before i hand the keys over to the stealership.
God bless you if you can help...

 

Control panel/ system and security/ adminastrative tools
i appreciate the input... at this point i'd piss on a pig if i thought it would help... it seems the dealerships are looking for us to solve the problems for them. otherwise they just keep throwing parts at it... mostly expensive ones. i was kind of thinking the same thing with the fuel lines. hope that's it... i'll post the outcome.