Hello sir,
Like I said before I think there should be no need to fatten up 909/808 samples if they are Goldbaby or Alchemy.
Maybe it's your over all mixing that needs some attention?
A lot of people who are starting out fill up their tracks with too much sonic information and have the bottom end muddy so that the kick clashes with the bassline, making the kick disappear. They then think that they need to fatten up the kick when in fact it's the stuff around the kick that needs thinning out.
Same goes with other drum parts. Listen to the tracks you like and listen to how much space they have within them.