pucuk

my land rover was powered by RB20det manual tranmission powerplant. My problem iswhen i rev up till 3000rpm to 4000rpm myy engine start jerking and loss a power.i was change my fuel pum with the brand new hi pressure fuel pump,spark plug,ignition coil(2nd hand) and many part are related in ignition system.I am still facing the same problem. my question is. Is that possible if i say that my problem are causes from the failure of O2 sensor? can anybody give me an answerfor that matter