there was an episode of the cosby show called "Cliifs nightmare" from 1990 which had some muppets in it.
which ones were in it?

I'm a HUGE Muppet fan, and I just saw this for the first time a few weeks ago! :)

Known ones were Gonzo, Sweetums (not performed by Richard, though), and Digit, then there were lesser-known ones only big Muppet fans would know (purple Frackle, Boppity, Luncheon Counter Monster), and the classic talkin' food (which sang some numbers on "The Muppet Show") was in the fridge. :)

There were also other random ones that weren't really in anything else.

I liked this episode with the muppets (I grew up watching Muppet reruns)! One thing that I noticed is that this must have been an episode originally slated for season 5 because Vanessa has the slanted afro do!