I probably average 2 or 3 Roms per week with my Droid. Recently I have been having about 1 in 20 luck with getting a Rom where the keyboard will work awesome. The other 19 out of 20 roms that I flash, they keyboards kind of suck (the true multi-touch implementation just isn't that awesome) I have fast thumbs and it is really annoying to have a crappy keyboard all the time. Always try the Android keyboard, and Smart Keyboard Pro on every rom (which I have found to work the best)
However on a lot of Roms, the multi touch will freak out and it will randomly switch to number, and just not press the correct buttons.
Why do you think this is?
Oh ya, and sometimes, the exact same Rom will work great one time, the i'll end up switching back to it at some point down the road, and it will not work good the next time.
PS I ALWAYS wipe and clear cache, so I doubt that is the problem