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!!!