Q: Valve cover leaking on to exhaust manifold gasket can that make it blow white smoke and make CEL flash

This is a fallow up question. Ok I know my valve cover is leaking can see where the oil is coming out of it like a stream. But was told it could be the valve seats. If it is the valve seats would it make a metallic pinging noise. The reason I ask is because I did not find oil in the radiator fluid and no radiator fluid in my oil. I'm losing oil from the valve cover. If the valve seats are bad could that blow my valve cover seal. And the previous owner installed a cold air ram air intake and removed the sensor and the air box. I replace the MAF sensor cleaned EGR and PCV and replaced vacuum lines but still get a air temp sensor CEL. Car runs smoothly but will die and won't start like no spark but after 5min it starts right up. So could the valve seats make the car idle rise and drop 500rpm and cause the white smoke out the exhaust pipe and blow the valve cover seal? And if so how do I check it? I'm grateful for your support and thank you for any advice given.

My car has 180000 miles.
My car has a manual transmission.