Hi, my name is ***** ***** you for asking your question, I will try and help you out.
If the check engine light does not come on during this low power issue the two most common problems are low fuel pressure or a leak on boost side of turbo going through CAC (charge air cooler) all the way to intake manifold.
Since you already changed fuel filters I would next check all your plumbing from turbo to intake,this includes all hump hoses,,hump hose clamps missing or broken, any damage to CAC.
Look on the inside of each hump hose they tend to rub on things and get holes in them.
Check welds on CAC, they tend to crack, especially if mounting is loose, so try moving around and check mounting bushings/bolts.
Run engine around 1000RPM and spray entire boost side of turbo with soapy water solution to see if you have any leaks (bubbles)
Remove piping from air cleaner to turbo inlet,,spin turbo to make sure it does not scrape and spins smoothly and not a lot of play,,you would see scraping on housing if to much play,,if it does not spin free its going out and needs replacing.
Questions or problems let me know I'm happy to assist