car has 250k miles running very rough and when it starts there is jingling noise on 2004 Cadillac SRX

never had tune up or timing chain done??

Asked by for the 2004 Cadillac SRX
jingle or rattle sound. poss. cat. conv.
rough running. review when last tuned up. it may be due.
rec. tune up every 50,000 miles.
rec. fuel system clean. ethanol treatment to 1 tank premium fuel.
rec. oil stabilizer treatment with next oil change.
thank you it never has had a tune up i have had it for the last 220k miles
no prob. good day.