Ulf-
I get your problem...your finger volume is INCONSISTENT, right? If so, is it "inconsistent" from the get-go or does it(the "volume")lessen over the course of the song?
If it's the latter, then it's only a strength issue; if it's the former, then it's as JT sez, practice while paying close attention to what you're doing. Scruntinize yourself; if possible, record your playing & take note of what's happening.
Too, typically, as a player plays faster, he will tend to play "harder"(ie "louder"). Unless that's the desired effect, watch out for that...it takes some discipline to battle that one!
