Spark Plug Fouling: Causes and Solutions

Hello,

I recently replaced two faulty glow plugs in my Passat 3B with engine code AHU, and I noticed some brown deposits. Could this be a sign of faulty injectors? However, the glow plugs weren't burned out, and the fuel injection timing was corrected about 10,000 km ago (it was significantly delayed). I also don't know how long the car was running with the defective glow plugs, as I only bought it in August.

I suspected the nozzles because the car doesn't start immediately (takes about 2 engine revolutions), it runs very unevenly when cold, and it doesn't reach its maximum speed.

'No errors are stored, fuel consumption is normal. I haven't performed a compression test yet because there is no excessive oil consumption (approximately 0.5 liters every 7000 km).'
The mileage is approximately 180,000 km.

Best regards,
Jens