Maxxforce 10 low power MAF Cal failed

I'll start by saying I dont own or drive an 18 wheeler but I am really struggling for help. I have a maxxforce 10 in my motorhome. It died on the side of the road but was running great prior to that. I had to towed to international dealer and they wanted 30k and had a laundry list of stuff to replace. They replaced the HPOP since it wasnt building pressure. Motor was able to run again but hasnt been the same since. It has a 6 speed allison and is a dog in 4-6.

Ive replaced
EGR Cooler had a coolant leak
EGR valve
EGR Mixer duct ( was fused to egr valve)
Converted to open breather
Cleaned L/H turbos
I've run every diag test and all pass except I cant do MAF Calibration. I get SPN 1209:0
MAF Cal throws code when notice surging? out the exhaust
I tested BCS and wastegate actuator.

Anyone have any thoughts? I'd really appreciate them (other than get rid of it) as Ive heard that too many times.
Much appreciated.

 

Thanks for the responses. Deleting or swapping isnt in the cards for me. Just trying to improve the shortcomings as best I can. I tested the back pressure valve with 8 and 21.5 psi and it worked as specified. I had looked at the doc and dpf earlier and the looked great (to me, no cracks or melting) The DPF did have a heavy amount of soot that seem to be collecting along the gap where the filter media meets the cannister. I will try to separate the down pipe where it meets the doc and retest today.

 

I do, hopefully this is allowed?

I sure do.

 

Ok so Im pretty upset now. I pulled the crossover duct to see if it was clogged and its fine. BUT, there's moisture pooled up in the egr cooler. Its brand new with only 5hrs maybe on it. Could I have caused something for a new cooler to fail?

 

Looked like clear sooty water not coolant. So it looks like its most likely condensation, sorry for the panic. I ran the motor with the crossover off and it dried up.

I apologize for being all over the place but I may have made a discovery.
Test 1: Ran MAF Cal with doc but no DPF.
EPB too high, noticed significant exhaust blowby on EGR cooler where it meets exhaust manifold seals. Shutdown test immediately after that.
I confirmed wastegate and EBP valve were not extended during test

Test 2: Ran MAF Cal with No DOC or DPF
It ran a little better (no blowby) but I notice "fluttering" sound from tailpipe while at full load. I could visibly see the exhaust come out of the 3" tube in "quick puffs"? Then throws code EPB above desired and test fails.
I confirmed wastegate and EBP valve were not extended during test

I have no idea if this is helpful, but any insight is much appreciated.