I'm trying to address the flaky(?) NIC in idaho (look here).

The command I use on idaho to force the nic is:
mii-tool -F 100baseTX-FD eth0
where mii-tool is the app, -F is force 100baseTX-FD is 100 baseT full-duplex, and eth0 is the nic you want to force.
NOTE: mii-tool does *NOT* work on gigabit nics. I haven't used this but the man page for ethtool says this:
ethtool -s ethX [speed 10|100|1000] [duplex half|full] [port tp|aui|bnc|mii] [autoneg on|off] [phyad N] [xcvr internal|external] [wol p|u|m|b|a|g|s|d...] [sopass xx:yy:zz:aa:bb:cc] [msglvl N]

So I'm guessing that one could do something like:
ethtool -s eth0 speed 1000 duplex full
and get the same results.