1989 300e Won't hold idle when warm until...

The engine starts well when cold but won't idle when hot?

How is its hot start?

When driving and lightly accelerating from say, 37 to 40 mph, does the engine bog down or does it accelerate smoothly, without complaint?

You've replaced the ignition parts, have you used any fuel injector cleaner to clean the fuel injectors?

It starts right up when hot, but shuts off immediately, I have to hold the idle at around 900 rpm, place it i gear and two foot it until it shifts.

Sometimes it is sluggish in the 37 to 40 range, but most of the time it is ok. I hadn't bothered with Injector cleaner since I run only 93 octane (can't find 91 here in Indianapolis), but I will give it a bottle.

Also, when it is warm, it regularly is sluggish from a stop, and many times shifts into first gear to get moving, which causes wheel spin on shifting to second gear which I think is a vacuum leak.

I'd suspect the MAS (mass airflow sensor), given these symptoms of what seem to me to be fuel starvation (not fuel starvation from a dirty fuel filter, that would show on hard acceleration and hill climbing).

The reason that I suspect the MAS is that the engine isn't being fueled at very low rpms when the air velocity through the MAS is low.

Check that the physical connections between the intake manifold and the MAS are properly connected and snug. If so, then the MAS electronics should be checked with an ohm meter.

If it's defective shop around for a replacement as these are available from non-dealer sources.

Finally, forget the fuel injector cleaner, although it can't hurt.

Could that also explaing the low idle (400-500rpm) after it has been run on the road for 20 minutes? I will look into the MAF and see if it is OK.

Thanks