I have a rattle which I now think is the window in some way.

Symptom:
- Slight rattle when I shut the door
- Slight rattle when I drive on very low RPM (diesel engine), can get the sound if I intentionally drive away on to high gear or drive slowly uphill
- Severe rattle when driving on very uneven/unpaved roads
- Seems to not occur if I lower the window very slightly

I have read quite a lot of threads and just now tried to tighten the 4 door screws and also swapped all 8 plastic clips that holds the door cover. Window regulator or what?

What should I do next? Thankful for any and all help.