ive got a 01 gt with auto trans . about 3 weeks ago i noticed when i would floor it then it would bog down for a few seconds and then pick up . i cleaned the maf , tb . replaced the plugs , coils , pcv , iac , tps and fuel filter . ive got new o2 sensors to go in with a h pipe . it shows no codes , and i test drove it after each step listed aboue . the only mod to car is a cold air intake . what am i missing . it ran great before and just did this all at once . please help