rough, holding back as if not firing on a cylinder feeling??

[xtremejimmy]

Like the title says, when I put less than approx. 40 % throttle, the car is holding back (almost as if it is not firing on a cylinder until under full throttle). Then, when i get past 50 % throttle or more, it smooths out and pulls nice, smooth, and hard. I've also noticed that it stays that way (rough holding back feeling) till the motor gets to operating temperature. Then, its constantly smooth. I'm currently running the factory tune to see if that would help, but still the same thing. I went ahead and replaced all 4 o2 sensors about a week before i this happened. Then, I returned all 4 for another set of them, and still the same thing. Went ahead and went through 3 sets of spark plugs, and still the same problem. I cant figure out for the life of me what this is. Its driving me insane.

Edit* I swapped out the rear o2 sensors to each other. and now its the opposite, smooth when i start up, then rough once warmed up. I'm not sure if that is in direct relation with what the problem is. What could be the problem guys?

I did notice however that when i plug my diablosport tuner in and check real time data, it shows as the number 4 o2 sensor staying at a reading of 0 unless you stab the throttle, then it gets a response. the other 3 are constantly fluctuating.

k guys, i drove the car again, and it ran smooth once it was warmed up again. however, it did throw a p0152 code and P0300. it says bank 2 sensor 1 high voltage and multiple cylinder misfire.