I was just wondering how common it is for these engines to have some roughness while idling after a cold start, even after letting the glow plugs glow for some time after the light goes out. However if I step on the throttle a little and bring up the rpms to about 1000 it's smooth and if I hold it there for say about 20 seconds and then release the pedal then it usually stays smooth. Is this common? Or do you get smooth idle without throttle right from the beginning? I wonder if I have low compression in one of my cylinders. All my glow plugs are new and working, I had valve adjustment done a few months ago, and use Redline about every other refill.

__________________
2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL