Sounds like you need more cable tendion, Sram likes having the cable pulled as tight as possible before clamping it to the derailleur. Try unclamping the cable, set the barrel adjuster so it's got half to a full turn spare to decrease tension if needed, then pull the cable tight and at the same time push the derailleur a few mm in-board, then clamp the cable. If you've pushed it too far when clamping the cable you can release a bit of tension with the barrel adjuster.
Sounds like you need more cable tendion, Sram likes having the cable pulled as tight as possible before clamping it to the derailleur. Try unclamping the cable, set the barrel adjuster so it's got half to a full turn spare to decrease tension if needed, then pull the cable tight and at the same time push the derailleur a few mm in-board, then clamp the cable. If you've pushed it too far when clamping the cable you can release a bit of tension with the barrel adjuster.