1998 e320 runs rough, idle jumps to 2500 then stall
 

My 1998 e320 started misbehaving. I've been working on it off and on for a few months. Now that I need the car, I can't drive it.

Pulled codes in May got a P0400 so I cleaned out the EGR.

Fixed the code issue, but not the rough running.

Realized battery was weak from sitting, put a charge on it, and it holds the charge.

Now car won't keep a steady idle. Runs rough, speeds up and then stalls (cutting a fart in the process)

So I made a video and posted it to youtube https://youtu.be/FB0r20uRVc4

Additionally, after I start the car, if I press on the accelerator, I cannot get a steady RPM, and it doesn't seem to matter how much I press on the pedal.

Oh and one more thing, the O2 Sensor may be faulty, but I thought it was just a fine tuning trim O2 sensor. Car exhibits these condition when first started. It also seems like the very first time I try to start the car it doesn't start. 2nd attempt starts and runs rough.

Did you clear native codes before clearing OBD II codes?

I'd throw a crank position sensor at it.

Sixto
98 E320s sedan and wagon

native codes? the baffle vacuum control box was leaking, so I replaced it, still misbehaving,,,

I was thinking about the crank position sensor, but the problem didn't start intermittently when hot. It does seem like it's hunting for the idle though,,,

maybe I didn't let it warm up enough to pull a code,,, this time I got P0300 and P0302 random misfire and cylinder 2 misfire

As I learn these cars, it seems you have to clear module level codes using specialized equipment then clear OBD codes for which you can use generic equipment.

On any other car the symptoms point me to the idle air valve and related wiring.

Sixto
98 E320s sedan and wagon

Found my problem!!! The part load crankcase ventilation connector was improperly installed.

What is a part load crankcase ventilation connector?