I had a similar thing happen to me right after a 200 mile trip on my '86 300E. The car would run only if the accelerator was depressed a bit and the car would not idle. This is how I learned to drive with both feet . I was told to replace the idle valve and this fixed it. I assume the 4-cyl car should have something like this. It is a cylindrical part about 5X3 inches located on one side of the head. There are two tubes attached to each side.

...Another thing, once I got stranded at the grocery store because a relay went bad (i don't know the name but it had 6-cyl stamped on one side, and it was behind the battery). In this case the car would start for 1-2 secs and then shut down regardless of gas pedal possition.

I hope this helps