Problems after O2 install...need help

[cmccloud]

replaced all 4 O2 sensors on 1999 boxster....car now runs very rough, pops, misfires, no power, stalls...tried unhooking battery as I have done before so ECU would reset to factory baseline and re-learn correct fuel mixture parameters with new sensors....no luck yet...am I missing something...any helpful suggestions would be greatly appreciated.....Car is not yet throwing any new codes...I reset CEL with scanner before starting... after sensor install...