Zardnaar
Legend
The actors in the original film were good enough to rise above the cornball dialogue, but for Empire and Jedi...Lucas wasn't the screenwriter or director, unlike the Prequels. He did the story outline and was a heavy handed producer, but he didn't do any of the dialouge in Empire, nor did he direct Ford and Fisher together.
Ford and Fisher also did some off screen chemistry apparently. Her coke fingernail made it onscreen in RotJ.