The CO2% being under 14% is normally a good indicator that the cat isn't doing its job. I am not sure if that is your only issue with your HC's being over 1300 at idle. You might test the exhaust before the cat, and if the cat is working at all at idle.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed