I would rewash them in super hot water(turn you hw heater up for this and then turn it back down), in every wash I would add vinegar or calgon, and I would keep doing hot washes with something(like vinegar that helps get the detergent out, do you have hard water?)until there are no more suds(open it and check while it agitates)at all. This can take a LOT of washes, but then after that you can mess with your wash routine and find something that works for you. I *finally* have found a routine that works all the time for my family, and works with all my dipes. Oh! FOrgot to say I have hard water, and this is what works for us.
cold prewash
hot wash with 1/4-1/2 cap det, and 1c vinegar
hot wash with 1 cup vinegar
I have to do a load every day because we have 3 older kids in cloth pull ups, and VI wears a nighttime dipe, but we also do family bathroom wipes, and with 5 people that piles up quick. LOL