Drop in engine power on 2000 Nissan Frontier

Hello. I have a 2000 Frontier, six cylinder. Last month the engine power dropped dramatically after the engine warmed up__to the point that it is barely driveable. Again when the engine is cold it drives perfectly___only after warm up do I have the problem. The check engine light does not come on. Any thoughts?

1 answer
This sounds to me like an emissions problem like the o2 sensor or cat. convertors. Are you getting a code?