Subaru SVX won't idle

1997 Subaru SVX (Alcyone) LSi, 3.3L H6 engine.

My SVX was driven from Denver to Las Vegas, NV and it developed an odd habit where the RPMs would start to oscillate while on cruise control. I had to disengage the cruise control to get the oscillations to stop. Three days later I was driving the SVX to work and the RPMs started oscillating at idle and the car started running rough and it died.

These things have all been replaced with OEM grade parts: Spark plugs, electric fuel pump & strainer & fuel filter, Mass Air Flow sensor, new air filter and fuses.

The car starts up fine but after a few seconds the RPMs begin to oscillate. Then the car tries to recover, the idle becomes rough, and the the RPMs drop very low and the engine shuts off. Any help would be greatly appreciated!

I would replace the IAC (idle air control) valve. Only thing against this guess is that it sounds like the car is warmed up fully before youre having these problems.
Id spray some sea foam into the throttle body as well.

Its also possible you have a vacuum leak of some sort.

I agree with the vacuum leak. An intake manifold smoke test can ferret out a vacuum leak quickly and easily.