Strange DPF issues

[Matt]

First off, I'm new here and thankful I found this community and thankful of all I've learned so far about my engine, i'm excited to be here.

I've looked extensively online in forums for this problem but no real info on what could be causing it. During an active regen I started noticing bluish white smoke on shifts, and longer if I'm pulling a hill. This was last week and after the regen was done all went back to normal, I had full power the whole time. Yesterday I rolled into a city and had to stop at a few lights, I noticed I was doing a regen when I got to the light (HEST came on), after i took off from the last light and started to accelerate I noticed I had very little power, and was getting the odd bluish white puff from the stack, boost was at 25psi on the dash (usually between 30 and 40 on WOT). About 10km later I got up to full highway speed and it seemed I had my power back..odd. I stopped a few hours later and was greeted with a CEL after a few mins of idle. I shut the truck down to eat and when I started up again the light was off, full power. Started today, no problems for most of the day, around 5pm I hit a construction zone and slowed down, after I was clear I went to accelerate, same BS, this time I couldn't detect smoke in the mirrors (hard to see, stack on the back of the sleeper), but no CEL until about a half hour later (still no power) basically stayed like that until I unloaded and went home although after i dumped I could get over 30psi on the boost but didn't get there all that fast, the truck still felt sluggish.

THAT SAID, tomorrow the truck is going into our company shop where I will have access to Insite, and I will be looking at doing Rawze's EGR tuneup (this truck is relatively new to me). What things in Insite should I look for to help diagnose this problem? anything I should do above and beyond the EGR tuneup? I'll list specs and what info I know below to help you wizards help me..

2008 KW T660, ISX485 (CM871 CPL2733) Turbo/actuator done mid June - 5000km on it, originally 485 but "bumped" to 550 by Cummins when they inframed it 30000km ago (i'll be verifying its a compatible CAL after reading rawze's post about bumping power - didn't even know you could mess that up with a Cummins tune) EGR cooler done a few years ago. Uses no coolant that I can detect yet and as for oil it seems that it's not using anything significant (ive had this truck on the road since AUG 1 so i'm still learning it's patterns) also the IMAP sensor is clean since i pulled it and checked (until this forum, that's all i thought was needed).