Hello
My 1999 e320 had the intake manifold changed due to the vacuum line being broken.

Also MB techs did the job with the valve covers and some recall items.

It ran good before, but now runs bad really bad.

Had issues with battery not starting.
The serpentine belt broke, replaced the pulleys, tensioner and belt.

The check engine and BAS light are on.
Two weeks ago MB techs scanned it while in the shop and found the brake light switch bad.

But how can a bad battery cause this or is it something else?

To me it feels like either an air issue, like fluttering when accelerating.
I will scan it for codes and report back.


.

I hope you replaced the bad brake light switch.

My best guess on the check engine and performance issue:
* A damaged gasket.
* A sensor not fully connected.
* Wire harness damage.

.

__________________
ASE Master Mechanic
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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
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Heat exchanger durability.
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