Root how do i revert back to old rom

[jdmmk3]

how do i revert back to the 2.1 i was previously running. right now i have kaosfroyo and dont like it. can anybody tell me how?

 

[scary alien]

how do i revert back to the 2.1 i was previously running. right now i have kaosfroyo and dont like it. can anybody tell me how?

If you made a Nandroid backup right after rooting, but before flashing a custom ROM, you could restore that (if you still have it).

Otherwise, you could use this thread:

[ROM][10/20/2010]FlashBack21 v1 -Return to Factory Stock - UPDATED - xda-developers

You could also flash a very vanilla 2.1 ROM like PlainJaneT2:

[ROM]Plain_JaneT2 V2.0 7/18/10 Stock With everything ROOT!! - xda-developers

Cheers!