A little one maybe. „Wciąż” is still in regards of time. As in still meaning now or not yet. „Jeszcze” is more universal. Can't recall at the moment a situation, where you can use „wciąż”, but not „jeszcze”.
It seems to me slightly different, but yes, acceptable. Added.
"Jeszcze", for me, sounds a bit like "OK, some of my doubts are gone but I have new ones", while "Wciąż" more like "Well, some of my doubts are not gone yet". But this is obviously a subjective opinion.