You're back to 2.3.20, right?
It's VERY simple from there:
1. Get copy of latest (Build 19) CM4D2 from
CM4D2 unnoficial nightly links
2. Get copy of Gaaps (6/13 version) from
http://goo-inside.me/gapps/gapps-gb-20110613-signed.zip
3. Put 1 and 2 above on your SD card
4. Load D2 Bootstrapper and bootstrap and then launch CW Recovery
5. Wipe data/factory reset
6. Wipe System (and you can wipe Dalvik Cache and Batter Stats as well)
7. Use Install zip from SD card to flash CM build 19
8. Use install zip from SD card to install Gaaps
Reboot. You're good.
While running the CM4D2 ROM NEVER install or use D2 Bootstrapper, if you do you will bootloop and have to SBF. Only use D2 Boostrapper while running stock Froyo to get into Recovery to flash CM4D2.