I've always though that the Falcon's flight trajectory was preset. After all, the technicians messed up its hyper-drive, maybe it was programmed to fly towards the Executor? Yes, it does have the plot-hole that they went to get Luke first, but still..

Also, I'm not sure how it is explained in the EU, but can a ship's tractor beam hold on to another ship, if the latter engages its hyper-drive engine? Maybe Lando and Chewie didn't care about the tractor beams (and thus flying towards the Executor), as long as they got the hyper-drive working.