For a couple of years i have been hearing this rattling underneath my car, couple of techs have told me off-back to replace converter. I have had this loud rattling for about 3 years but, my check engine light has just now illuminated. After a tune-up a couple of months, I started feeling my engine performing a "backfire, jerking" maneuver. When my vehicle is driving on even a slight incline or uphill, it is difficult to get any power when acceleration is increased. I am a beginner DIY enthusiast and I would appreciate all and any info regarding this concern. Thank you