I am not aware of any such mods. However, you could do something like the following:
1. Using the Construction Set, ncrease the number of skill increases needed to level up to something large (3,000 should be high enough; note that, from what I have read (haven't tested this), the game only saves the low byte of the number of skill increases since the last level, so values > 255 will decrease).
2. When you feel that you should level up, use a console command to force the level up. (I believe it's EnableLevelUpMenu in Morrowind; in oblivion, I believe it's advlevel.)

I'm not sure the MCC Leveler is exactly what you're looking for (I've never used it myself):
https://www.nexusmods.com/morrowind/mods/44294