My check engine light when on and found out it was a bad knock sensor and a rear engine O2 sensor, which I can replace. However recently, my car doesnt accelerate properly. WHen shifting from 1st to 2nd it seems to bogged down. Almost a stuttering affect acceleration. What could cause this. Someone mentioned that if you have moisture in the engine that this could cause it. I do have an CAI which goes down near front left wheel well. If this is true, anything I can do to fix..

HELP

 

Fix the O2 and KS. This should clear things up

 

o2 sensor is the piggy back code, fix it/clean it/repair it..do whatever you have to do, but once that problem is solved, the KS code will usually go away and you will most likely gain back your acceleration.