To summarize there are two problems:
1. Uneven layers, similar to Z-wobble, except it's random, not regular.
2. Small "blobs", which I think are typical of wet filament, but I have tried with known dry filament (PLA and PETG) and got the same result.

Since my last post I have replaced the nozzle and PTFE tube. This resultet in no difference in print quality.

Any suggestions?