Turbo on my S60 Detroit isn't working right

I noticed yesterday that I'm now getting a shuddering when I'm in gear and the speed of travel has dropped a little from traffic or I'm starting up a hill. This seems to be related to lower RPM's, like below 1300, and if the speed picks up enough to get the RPM's back up, it stops the shuddering a acts normal.

Back story: Had ECM re -flashed in Effingham Feb 1 ...then a new Turbo was installed a week later along with a new EGR cooler, and Fan Clutch assembly..... another 2 weeks later my EGR valve stuck open......that was replaced, and everything has been normal.....or at least seems ok. Fuel mileage is running mid 5's for heavy hauls, to as much as 6's if under a light load....and I cruise at 1525 RPM's usually, which seems to be better than a lower speed with a 1400 RPM as cruising. That is 67 vs 63 mph.

The turbo had a fair amount of lag in it when I took it to be re-flashed.....that was changed to no lag. I turned hp up to 595, and injectors set to operate at .75, along with what ever else they set up in the ECM .....I don't usually have to drop a gear on many hills, and if it is a steep enough, I lug it to about 1000-900 before downshifting. and I don't rev it above 16-1700 on the pull, and actually try to be just at the 1525 range, then.

Not sure what to expect, but I'm thinking I'm looking at a trip into the lease owner shop for them to check it out. They know I changed the ECM and didn't seem bothered about it. If it is related to the ECM re-flash, I'd sure like to know why.

 

Ok, I maybe shouldn't be lugging it that low, but the fact is, the shuddering happens when I let off the throttle and then get back into it..... level highway, or up a hill, doesn't seem to matter. I'm just saying that it is low revs that seem to be a factor, and it wasn't before this trip. I wasn't getting the shuddering at the low revs. Just solid pick up. I'm guessing the variable vanes of the turbo is somehow at the heart of this......they found the old turbo had the adjuster rod stuck, although I don't remember this severe level of shuddering, I do remember the lack of pick up. It was one reason I went to have the re-flash done. More later after I can get it to the shop for them to check.

 

So as it stands, it will mostly hit my MPG when I'm traffic where I get off the peddle and then when I get back in the pedal, it does it whether I ease onto the pedal or just get back into it.

 

Well, I don't know where my head was yesterday when I said I lugged it down to 1000=900......I realized today what a newbie statement that made me look like! I don't ever go that low and at most I down shift at or before I get it to 1200. And again, I hold a downshift at around 15-1600.......And with summer approaching I never climb a hill by trying to power it up the hill, but hold it at RPM's that doesn't cause the temp to rise to high, and that could be as low as 7th gear to keep revs up to help temp stay down to normal range.....No sense in getting the head damaged.