1985 380sl hard cold start followed by no warm start

[pchmalibu]

1985 380sl with 200k+ miles does the following;

Cold, starts on first crank, idles @ 5 - 600rpm for a few seconds then stalls. It will re-start and immediately stall. Depressing the accelerator stalls the car right away. A few squirts of starter fluid allow it to start and run well enough to press the pedal to get the rpms up and keep it running. After 3 mins it will idle but it seems to constantly cycle between 600 and 630 or so and then fall to 350-400 every 10-12 seconds. If I bring the idle up to a steady 2000 it will still cycle between 1970 and 2040. I turned the car off and tried to restart after 10 mins. but it just cranks and cranks with no sign of starting. A few squirts of starter fluid made no difference at all.

If it is a fuel issue wouldn't the starter fluid at least fire her up for a split second?