I made that drain/fortify strength spell I mentioned in my "custom spells" topic (made it Target with 10ft. area) and fired it at a Cliff Racer and it was suspended in mid-air. Why didn't it fall? (I didn't bother to kill it, so I don't know if it was actually carrying a Racer Plume.)

Also, why hasn't anyone else posted in my custom spells topic?

If you want it to fall, cast a levitate spell on it and it will fall when levitate wears off.

This forum isn't very active for Morrowind because, unlike most other old games, it still has a very active official forum and modding community. You will definitely get responses there.

There are several mods dealing with this issue available - see nexusmods.com (for example, search the Morrowind section for "cliffracer"). Here is one example (which I haven't tried myself - for me, cliffracers are a part of the atmosphere of Morrowind), which let's you choose between removing them, making them non-aggressive, reducing the spawn rate and making them less aggressive: http://www.nexusmods.com/morrowind/mods/277/?

Here's something interesting that happened while playing. During an escort mission, I saw a Cliff Racer in the distance and decided to cast my Strength lowering spell at it. The Cliff Racer froze in mid-air, my escort ran after the Cliff Racer and started attacking it, and the Cliff Racer started animating and attacking the escort.

The game is weird sometimes.

It's the cliff racers - they pretended to be affected by your spell, but are immune to it. Never trust these guys! -:)