If KIES installed, please kill KIES and every KIES and Samsung Process running in background!
Run Odin as Administrator.
Uncheck "Auto-Reboot" in Odin, also make sure "re-partition" UNCHECKED!
Add the recovery.tar.md5 as PDA.
Boot into Download-Mode and connect it to your PC - Odin will show "Added!"
Now Press Start.
When Odin finished flashing: wait 1 minute.
Now press Power-Button & Volume UP at the Same time! Keep them pressing!
When you see the Samsung Logo, stop pressing the Power-Button but KEEP PRESSING the Volume UP button for 5 Seconds.
Itīs all about timeing. Also make sure you are using the right recovery for your device!
What error are you getting exactly in Stock Recovery?
Can you still boot your Rom (even if it reboots)?
Else you can try flashing the recovery.img using Heimdall (you can extract the recovery.img from the *.tar.md5 using 7-ZIP) - but donīt ask me for instructions on Heimdall
itīs different from Odin - but as i read it seems to be safer.