Check engine light is on, code reads multiple misfires, clattering noise in back on 2005 Cadillac SRX

of engine, noise kind of quits when you accelerate out on the highway, what could this be, car has 73000 miles on it??

Asked by for the 2005 Cadillac SRX
have you ck'd all your fluid levels, like oil and water? sounds like a lifter noise.
Have checked all fluids, they were all right, what else can I check, car has given me nothing but trouble as long as i've had it. Replaced timing chain a year ago, also new struts($1600.00) Got to get rid of the noise so I can trade the LEMON off!!!