When i first start my car up it starts like normal then after about 2-3 seconds it drops in rpm to around 400 and bucks and sputters hard. If i try to feather the gas it just kills it. If i just let it buck for around 30 seconds it idles up and runs a little better. I can't figure out what the hell is going on with it. Also, When im accelerating it feels like the car is lacking its nuts. Kinda like its being held back. But if i got wot, the car screams. I replaced one of my 02 sensors the other day and it is running a little better but still having the issues above. I think i might replace the other 02 sensor since it is original and the car has 110k on it. Oh and the mods are Pypes Long tubes, Pypes catless H, SLP lm1 catback, Professional products t.b. and plenum, Mac Intake, Diablo Tuner, Supercar pump with pprv delete, Centerforce df clutch. I have had the same issues with the car since i bought it.