you can try tuning with fakesmc guide thats posted on the site or edit the dsdt and search for Geforce 8400 then replace with what you want to see. there both in the same family btw.
have you tried naming the kernel during chameleon boot? type in
mach_kernel -v
add any other flags your using. maybe there is a volume path entry in org.chameleon.Boot.plist for the kernel that does not exist on your machine.
it could be that the first time it boots it is without kernel cache by the second time it has built one and booting from it. try booting with out cache option. -f
did you install the mod kernel on your new install you would have to replace mach_kernel also if the modded kernel has a different name rename it to mach_kernel if not the cache's will not get built properly.
idk from searches it looks to be a normal d630 but the findings where a bit vague. is there any way you can install a newer version of snow leopard? the boot packs over time have been upgraded to conform to newer installers. maybe that's where the problem lies? or you can start with whats working like the generic boot pack and slowly integrate the boot pack files till you find whats causing the issue and report back.
according to this blog http://blog.stuffedcow.net/2012/07/intel-hd4000-qeci-acceleration/ there are 4 choices for 64 mb ram. IntelCapriFB= 2,3,8 & 9 it correlates to the last number except for a & b chameleon calls a=10 b=11