2002 Chevy Tahoe Engine "knock", Maybe Knock Seno

I own a 2002 Tahoe with 107,000 miles. It is the Big V-8 5.3. Around 95k miles the Service Engine Light. I downloaded the faults and had 2 faults for running Rich and 1 fault for a miss fire. I have replaced all 4 o2 sensors and now the only fault is the miss fire. The engine itself works great after a 15 minute warm up period (during the warm up period, RPM's flux betweeen 200 and 1500) It has actually died a couple of times. It also has a "surge" like feel to it at stop signs and red lights. I was wondering does this sound like a possible set of bad knock sensors or should I be looking somewhere else?