the nexus s 4g was performing worse every day - slow, low memory - a great candidate for the known advantages of a custom ROM.
I followed these 2 videos and was successful - and it was much easier than i thought.
I used the pdanet installation instead of method #3, and also had to manually reboot from the recovery console (happens to the guy in the video too). I did not bother with the super user or busybox install since i was going to put a custom rom.
The ROM i found was best for the nexus s 4g (stable, feature full, lightweight, people happy, active development) was SlimBean - http://slimroms.net
don't forget the gapps from the addons section.
official thread from xda http://forum.xda-developers.com/showthread.php?t=2060483
I backed up all the pictures, sounds, and did a factory wipe. I cleared all the caches before and after installing. In the first boot, the slimbean logo kept flashing - I booted into recovery mode, wiped caches, installed gapps again, and wiped the caches again, and that fixed it.