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Q: Loss of power and rattling from back under part 1998 BMW 323

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The car runs but when I get to a higher speed like 50 to 60 mph the car loses power and starts to shake ,I have to pull over then it dies..I left the car without driving for a few days then I turned it on and the rpm was slightly under the 1where it usually sits...and when I press the gas slightly I can hear a metallic rattle coming from the rear under the car..the car stays on I took it for a test drive it did good while going slow but a the speed when up it started loosing power.what could be the problem

My car has 140000 miles.
My car has a manual transmission.

Hello - I believe you have 2 unrelated problems: the loss of power, and the rattle. I believe your loss of power problem is either a failing fuel pump, or possible a clogged catalytic converter. The fuel pump issue would have been noticeable over a few days or a week, whereas a clogged catalytic converter might have taken a period of weeks or months to notice - slow decline in power. If there are problem codes stored (Check Engine light), they will be most useful in diagnosing this problem. I would recommend an inspection to determine the source of the loss of power by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs. I would also recommend YourMechanic to inspect the vehicle for the source of the rattle you have observed.

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