Corey Feldman is clearly in demand -- in his own mind -- because he's not jumping to sign on for a "Goonies" sequel unless producers meet his demands.
TMZ broke the story ... "Goonies" director Richard Donner says he's making a sequel to the movie 28 years later and wants the entire cast to return -- but Feldman's not down just yet.
Feldman unloaded online saying Donner tried selling him a similar story a few months ago -- Corey claims Donner promised Spielberg was involved as well -- but he's skeptical.
Corey adds, "It can't be done without a perfect script! We all must be certain that it doesn't miss the magic of the original."