'90 transmission stalling

My '90 Chevy Lumina works excellent except that on mornings or if the car stands for 4-5 hours, when I put it in drive (D,1 or 2), I must rev the engine hard many times before the drive engages. However, when I put it in reverse, it ALWAYS engages immediately, even on mornings. What could be the solution to this problem? Help anybody....

the foreward clutch is damaged in the transmission////YOU need a
re-build,used,or repaired. don't waste your money on flushes, filters
ect,ect.