Loss of power

Good morning,

I would do some basic checks first.

https://www.2carpros.com/articles/engine-has-low-power-output

I would check the fuel pressure.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

I would also do a cat converter test to be sure the catalytic converter is not clogged not allowing the engine to breathe.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Roy

How do i check the catalytic converter?

You would need a back pressure gauge. You can get one at a parts store and remove the O2 sensor and install it. Start the engine and it will read a pressure. Anything greater than 1.5 pounds means it is clogged.

Otherwise, you could drop the head pipe to the exhaust manifold and then take it for a drive and see if it still has the issue.

Roy

Up upstream or downstream?

Upstream sensor.

Roy

Someone told me that i can test it by taking the up stream o2 off to check it. do you think it safe to do?

That is not enough of a leak to test the back pressure.

Dropping the pipe is the best way to test it. Or, get the gauge and put it in the upstream O2 sensor hole and measure the back pressure.

Roy