I would think 8 lbs of grapes for 3 gallon would be way weak. I would have used about 30 lbs for a 3 gallon batch. you could add some frozen concentrate and a little sugar and maybe bring it around. hope it turns out for you.
I had the same thing happen and I switched to the silicone type and it went away, as for what you have done all I can say is it will get better with age if it is coming from the rubber bung. hope this helps:fsh
I have made only one batch of pineapple and took months and months to clear. I racked it about every 30 days to help in the clearing. but finally I got it to clear. other than filtering that is about the best advice I can give you. hopefully one of the senior members can help some more..