'88 240 DL
I've been puzzling over this for a week now.
When the accelerator is depressed, the car will bog and stall.
Symptoms came on suddenly, NOT over time.

Upon initial inspection, I found a large tear in the intake hose between the TB & MAF sensor.
I ordered a new one and duct taped the old one to limp around 'til the new one got here.
BUT, no change, same symptoms.

I delve further and find a hole in a vacuum line which I repair.
I then remove and clean the throttle body (it was dirty).
TB sensor clicks when it should.
Still no joy.

I remove the ACV. It is stuck so I clean & replace.
No joy.

I remove the cap and it and the rotor are fine.
The wires are 2 years old and show no sign of wear/arcing.
I remove the plugs and they are pitch black, very rich mixture.
I suspect this is traceable to various air leaks and OxySensor/computer compensation?
I replace plugs with new.
No joy.

The only thing I have not done yet is inspect/clean out the breather box.

The car has a rebuilt MAF sensor about 2 years old.
The ACV opens about half way when the car is running but then stays there. There is continuity between all 3 terminals, approx 20 ohms btwn ctr and both ends & approx 40 ohms btwn both ends.
Is it supposed to open/close rapidly or just open to a happy spot and then hang there? I have not seen it close on its own. If I manually close it, it will open.

What am I missing? Any thoughts?