question: 190E 1993 start and stall. Please help.
 

My sister has a 1993 190E. I chose it for her years ago when she gratuate. It's kind of a memory car for both of us.

around 2 years ago, she bought a new car and left this car sat since then. Last weekends, I went to help clean it up to sell it for her and found a problem. After jumped the battery, it started right away and idle a little low, around 700rpm, then it came down to 500rpm (in several seconds) and stalled. Restart again, same thing.

Today, I went to see if I can fix it. After cleaning up the cap, rotor, spark plugs, ect, no help. It started right up and idle nice for several seconds, and stalled. If I keep my foot on the gas, or tab it when the rpm comes down, it won't stall. I leave the pedal alone, rpm will come down to 500rpm and stall.
I even open open up the air box lit and let it idle, same problem. Then I tried to tab the gas pedal and shift, it stalled too. When I kept my feet on the gas pedal to have the rppm above 1000 while shiping, sometimes it will stay on but it shake hard when I shift, sometimes it stalled too.

Anyone know what the problem is?
Thanks in advance.

I would try fresh fuel before I did anything else.

Check the Micro-switch on the throttle assembly.

- meaning drain the tank and refil with new gas? Could you elaborate a little detail on how to drain the tank?
- I check the little switch (with a little wheel/bearing type) under the carb air box, on the U.S. driver side. Look like it's clicking fine. What does it do may I ask?

Well, you implied that the car sat for 2 years so I would want to make sure the fuel is good. I experienced old fuel in my Corvette a few years ago and it wouldn't idle until I replaced the old fuel.
It depends on how much is in the tank....if it's low then you could add some fresh 93 octane. If it's 1/2 tank or more then you might need to drain some.

The micro-switch is a fuel shut off. If it is working correctly you can test it buy holding the idle at 2,500 rpms and push the micro-switch button in and it should lower the idle.