Not imitating to sound like the singer but..

Not imitating to sound like the singer (tone) but I end up constantly picturing how the singer sings the song and it messes up with how I sound.

Eg. Following the singer's dynamics but it just sounds totally off when I sing it. Like I'm trying really hard to follow and end up very pitchy and 'unnatural'.

Has anyone gotten this problem before? How did you get over this phase?