Mlox had the following to say about this mod:
"MQE_BlightedBeasties.ESP" (and so the merged "MQE_MainQuestEnhancers.ESP") uses AddToLev*/RemoveFromLev* functions to modify Bethesda's leveled lists. Using either of these plugins will store leveled lists in your savegame that will override lists in your merged leveled lists plugin (e.g. "Mashed Lists.esp"), if you have one.
abot has released a version of "MQE_MainQuestEnhancers.ESP" which does not use these deprecated functions, and makes some other improvements and fixes.
Download "Main Quest Enhancers 1.03" from abot's website - http://abitoftaste.altervista.org/morrowind/index.php?option=downloads&task=info&id=72&Itemid=50
The plugin mentioned by the Mlox message is next up (if you're following the Total Overhaul list)! Since it's replaced by the patch, you technically don't need to download this mod. I am keeping it listed as a reference.