My 99 CV falls on its face if throttle is past 50%...I installed new oxygen sensors

Could it be the fuel pressure regulator? im lost and i just want it to be back to running right. By the way 304,000mi and still starts perfect every time. Take care of them and they will take care of you. Yes it is the original motor, trans, and rear end

Check your o2 sensors, and if the one by the air filter is dirty get some oxygen sensor cleaner from autozone or advance auto. It is a liquid spray but made especially for O2 sensors. This may help your acceleration and your fuel consumption it has helped mine dramatically.

try cleaning the mass airflow sensor as well with some regular crc mass air flow sensor cleaner