The only way that could be happening is if you skipped the initial steps and just downloaded froyo, put it in the root of your SD card and tried to do the update (downgrade) without taking the initial steps necessary to fool the system into thinking you're on an older version, or you performed those steps but did not pay attention to the results and failed.
The OP included the responses you should see to indicate success on those steps, so there should be no reason to assume they worked and try to perform the downgrade.
My guess is you never tried them and just attempted the final step, hence it failed. If you need help I'll be glad to do what I can.
myTouch 4G - Black
Rooted w/ s-off
Glacier Gingerbread (2.3.4) MySense 2.1
ClockworkMod Recovery 184.108.40.206