2015 Touareg TDI injector problems

I recently deleted the EGR cooler and DPF on my Touareg with about 150,000 miles. After getting everything back together, I flashed a Stage 2.5 TuneZilla tune. Other than a small coolant leak from one of the coolant hoses with a banjo fitting, everything seemed fine initially.

A couple of days later, I noticed a rough idle. I checked VCDS and found cylinder 3 injector deviation at +5.03 mg/stroke, and eventually started getting cylinder 3 misfires. I limped it home, cleared the codes, and later that evening started it again. Surprisingly, it smoothed out and the injector deviations went back to normal.

At first, I thought maybe I still had air in the fuel system from the work I had done, but I should have known a VW wasn't going to fix itself.

The vehicle then ran perfectly for almost a week before the exact same problem returned on cylinder 3.

So far I have:

• Cleared codes multiple times
• Checked injector deviation values in VCDS
• Run the fuel pump test
• Run injector tests
• Reset injector adaptation values
• Monitored rail pressure (actual vs. specified)
• Verified actual fuel pressure closely follows specified pressure
• Checked that the glow plug connector was fully seated
• Tuned the vehicle back down to Stage 1 to rule out the Stage 2.5 tune

Unplugging injector #3 while the engine is running causes little to no change in engine operation. Unplugging the other injectors definitely affects the idle.

Before I pull injector #3 and swap it with another cylinder to see if the problem follows the injector, does anyone have any other ideas? In the past I broke one of the injector bolts off in the head so I only want to mess with them if I have to. Plus I will have to buy new bolts and crush washers.