My 1995 Mercedes 420E bucks like if it is running out of gas!! but the engine never stop running. I have put it in shop 3 time now!!! I get the same answer very time if the check engine light don't come on we don't know what the problem is. Do anybody know what the problem could be???????

Sounds as if the engine control module has gone bad. Here's the funny part if the engine control module is faulty it will never know its faulty so it may never turn on the check engine light. The throttle actuator and the air flow meter can also cause driveability problems with the M119 engine. You should be able to pull blink codes from the 8 or 12 pin connector next to the battery. pull the little cover off the connector that sits on the firewall. With the key in position 2 and the engine not running push the little button in for 3 seconds and watch and count how many times it flashes. If it flashes only once then that means no faults. If it flashes more than once then count the blinks and repeat holding for 3 seconds to see if there's more then one codes. This is checking the codes of the DM (diagnostic module) it should have a code if the engine control module is faulty. All this is assuming that all the initial step have been taken like checking distributor cap,rotor,plugs,wires and vacuum leaks.