Roll back iPod Touch 2g from 4.0 to 3.1.3

I upgraded to OS of my iPod Touch 2nd Generation to 4.0 months ago. and since then my life was in hell as the 4.0 was running in very slow mode every once in a while and I have to keep waiting from time to time until the device become responsive again.  Finally, I am ultra feed up, and decided to go back to iOS 3.1.3 for good (and probably never ever upgrade that device again).

Apple makes it so hard to DOWNGRADE a device.  If you just download the firmware from the popular firmware site, and then tries to install the 3.1.3 firmware by Shift click on [Restore], you will eventually hit the error 3197.  On the top of that, some people claimed that the 3.1.3 on felixbruns is corrupted. Maybe that's why I got the error 3xxx even though I following the instruction by hacking the host file.

Finally, I found the ultimate solution: just go to Sinful phone site, download the Custom Firmware of 3.1.3 specifically for iPod Touch 2G, and bam, problem solved.  3.1.3 completely updated without any error.

I tried the device and found it much more responsive than it used to be.