Bucking at2500 to 3000rpm in 2000 tacoma 4x4
 

I own a 2000 tacoma 2.7 5 speed at 2500 RPM in third gear it begins to buck if you shift into fourth gear it will go away untill 2500 again . you don't notice it in 1st or 2nd.The plugs are new I have scanned it and there are no missfire codes I have replaced the o2 sensor and the air fuel meter I am coming up empty here need a direction

I believe mine did the same when my TPS wasnt adjusted correctly, it didnt throw a code either.