Maxforce 13 yes another in need of help

I recently bought a 2013 prostar and from day one it's been a nightmare 5mpg bobtail 3.5 tridem van , I complained right from get go maxim a Canadian company that owns international dealership screwed me right off the start! Full disclosure was a contractual must in purchase agreement, they withheld most of service records untill after sale . Now I was blowing oil out exhaust no power when hot forget it I had to activate fan manually by 200 or major blue smoke after taking it into dealership told canny find any issue and handed me a bill, I'm on verg of bankruptcy and only owned it 2 weeks and dealership held truck for a week till warranty ran out and only worked on it 1 .5 days. After a go round I got pissed and said screw it and bypassed egr sysyem( read all training and service manuals) so far fuel economy went up waiting for load to try it but Alberta legalized egr delete and I don't run states so I'm thinking of doing it as I'm stuck with truck. I thought maybe piston cracked but still not 100% on egr system , if gone will it blow out oil through exhaust. This thing was like having potato stuck in exhaust but jaked(engine braked) better than a 600hp
Any thoughts as what's causing power fuel loss( used almost 1/4 tank idling for 3.5hrs at 800 rpm) I don't want to have to tear engine down to inspect all parts possible it had whole top end turbos and emission system replaced less than 6 months ago but blew egr cooler every 40k miles . Used very little coolant just started using oil
Thanks

 

Yes I did my homework, I knew a lot of the issues going into this. My main pee off is the service records provided prepurchase only showed a few minor issues since new (compared to 15 pages front and back received by accident post purchase) and compared to the service records of the dd15 I was looking at it looked better. I'm dyslexic and I'm the reading the manuals on a phone so it's hard for me to understand it all .My biggest mistake was thinking warranty was of use and that international knew more about the engine than I did. My main concern right now is how oil is getting into exhaust, can it come from egr system if so from where and how. I put 300 miles empty on it and used 1/16 of a tank of fuel ,far better than before. Oil and coolant levels unchanged I guessing I'm running around 25% egr( I didn't totally disable it) and oil no longer comming out exhaust. From the work I've done on it already I see a couple major design flaws in the system that are easily fixed. When I get home I'm tearing it apart to inspect pistons ,bearings and dye test head and really understand system. if all good I'll do delete until I make enough money to test some solutions I see as potential long term solutions for those that can not do deletes. Tomorrow I load test it and see how that works while I try and at least earn my fuel money home. Also does anyone know if coolant in egr cooler is connected to entire engine or seperate system in event it goes and has to be disable before I get homr

 

Thanks will do. I plan to install precooler expansion tank and manifold/turbo coolers among other things .