i like to know if i should leave my 02 because it look like it running ok but it the stock one that 10 years old whit 142,000 km or about 86,000 miles what do you think will i gain something if i buy a new one

this is what its look like

Well, it looks pretty clean and it is not blackened like alot I have seen. If your unsure of the state its in, then replace it.