Vehicle is a 2002 ML320 - started missing. Code pulled said "# 3 cylinder misfire" so the repair shop switched coil packs - all are good. Wires are good. Did a compression test with no problems. Have replaced 2 fuel injectors that looked suspect and replaced all spark plugs. $1900 in and it is STILL missing....
Any ideas?

Can you acutally feel it missing or are you just reporting OBD2 diagnostic?

Many times a "missing" diagnostic is cured by simple replacement of the MAF sensor--they are notoriously unreliable on this engine.

There are all kinds of OBD2 codes that trace to bad MAF and there is very seldom a code that actually says bad MAF.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

We shall see. Evidently, it was a coil pack - which is what I suspected all along. They switched them from one cylinder to another with no positive results. Three of them were bad.