i think i have a help for you my friend.
I had exactly the same issue, high idle cpu usage, at first i started deleting everything that was recomended (cpumem, flashlight extra etc), then installed power top and started monitoring the process, took a little to really understand the info (im no programer neither a linux user till now).
then i noticed that the phone was waking too much from sleep, about 1500 times as per power top, the most active process was the core with nohz process as i investigated a little ive learned that this was only closing application that were opened and did not clos alone when idle, so the problem was something else that was opening.
the next suspect was the mmcqd process, almost 60 times in 30 seconds, again i started looking and mmcqd was being used as kind of a back up due to a delay on the proccesing of data from the memory card (not still sure about this part, but i found reports of thsi kind of behaviour on n800 also). So i unplugged the microsd, voila almost tottaly flat for 9 hours, wakeups went to 600 on powertop and average time in idle per process is now about 2 sec (it was like 0,6 before).
the funny thing is that i only have music on the microsd, not a even on link to data needed by any other process on the phone. Ill start checking if this problem is from a defective microsd or is due to a problem with some kind of data traker (could be a tracker for music or general data, but again i have only music on the microsd) from linux (hope is the first one because i have no chance of fixing the second one).
Soooooooo fo make it easy UNPLUG THE MICROSD CARD AND ITS FIXED!
Kind of good and kind of bad, i really like to have 14gb more of musci on the phone.
hope this helps you!