W210 E320 rough idle/ misfire
 

I am hoping someone can help.

2002 E320 wagon 4matic 76k miles

Rough idle. No CEL. Definitely missing, can feel vibration in cabin at idle.

Pulled the following codes:
P0303 - 3rd cyl misfire
P0171 - Lean left bank
P0174 - Lean right bank
P0300 - Multiple misfire
P0303 - 3rd cyl misfire

What's been done so far.

We ran the smoke machine for air leaks.
EGR stuck open - Replaced
Dipstick tube o-ring - replaced
Sealed a couple of small vacumm tube leaks.
MAS - removed and cleaned with CRC MAF cleaner
Swapped Coil pack, wires and plugs from Cyl 3 to Cyl 1.

Reset Codes, re-read codes, pulled P0112 IAT Sensor. Looks like the IAT is integrated into the MAF sensor.

In my mind I feel it is narrowed down to MAF sensor, plugs wires or Coil pack.

Hoping for some suggestions rather than throwing parts at it. Any suggestions?

Thanks!!!

Most likely the MAF...

Of course the spark plugs are to be replaced at 5Years or 100K miles which ever comes 1st.

Update

Problem was bad plug wire. Initially the misfire code was Cyl 3 and random misfire. I moved the coil, wires and plugs to Cyl 1. Got too impatient for codes to show. Unplugged coil #1 without change to idle, replace those 2 wires, runs smooth.