Variation of W124 stalling problem
 

I recently bought a 1991 300TE 4Matic with 204,000 miles. It has been intermittently stalling when coming to a stop or slowing to make a turn. I've been reading up and seeing that this is a common problem attributed to many possible causes (I'm keeping a list of them).

But my car is doing something I have not seen described elsewhere. After stalling it will restart (though it requires a lot of cranking) but will die immediately on being put into gear. I go through this 8 or 10 times before it will stay running, sputtering, and get moving. Then it clears up and runs perfectly with no more stalling.

This seems to be a fairly neglected car in addition to the high miles, so anything is possible. But I wonder if anyone could suggest the most likely starting point for a diagnosis and repair effort. Many thanks!

Going thru the "basics" would be my starting point..
Plugs, secondary ignition, new filters, & compression test.

Once you have established that engine is in good tune & you are running a good grade of 91 octane, then start checking the fuel system.

Vacuum leak. If this is an M103 (SOHC), check for a split idle control valve hose, a leaking air flow meter horn to throttle body clamp, and broken vacuum actuator lines.

If the fuel pump relay is quite warm after short runs, replace it, a new one will cure all sorts of ills. Definitely bad if you get occasional stalls while driving.

Check the cap and rotor, a leaking camshaft seal will cause serious carbon tracking and difficult hot starts (crossfire).

Seconding MB DOC, plugs, wires, cap, rotor, good fuel, plug condition.

Peter

Thanks for the input, guys. The vacuum leak idea in particular jibes with past experiences. I had an immensely frustrating day today trying to change the fuel filter. Didn't really think this was the problem but thought I should change it on general principles. The one I bought at AutoZone turned out not to fit, though--it was at least 1/4" larger in diameter and would not slide into the clamp, let alone the plastic sleeve inside the clamp. Went running around to other parts stores and found only one other fuel filter in stock, a Purolator, also too large. Finally just re-installed the old one and moved on to do an oil change and replace the serpentine belt, two post-purchase jobs I didn't want to put off any longer. That went OK except that the belt tensioner bolt ran out of extension before the belt was tight, so I had to jury-rig a way to tighten the belt adequately. Is it just me, or is basically nothing easy on these cars? (Maybe you can tell it's my first experience with MB.)