Car keeps quiting
 

I have a 190e 2.6 1987 and when i try to start it, it quits. then when i try again i have to give it gas to start sometimes. and recently my car has had very very bad gas mileage please help
thanx

Definately a problem with the fuel system or ignition system. I'd check spark plugs, fuel filters, and anything related to the two systems that I would be able to check. Really sorry your 190 isn't running well, I love all 190s! I honk at all 190s I see driving heh heh.

Another possiblity I know of besides ignition or fuel system is a plugged exhaust system (front catalytic converter especially). I have seen a few of these, they act kind of like you say, you need to put the throttle down to get it to start, and if you let off the throttle it'll die. If you believe the engine is in a good state of tune, and it didn't start acting up right after getting gas (in which case I wonder if you got a bad tank of gas) I would think about this possibility.
To verify it, loosen up the bolts that connect the exhaust pipes to the exhaust manifold to relieve the exhaust back pressure, then see if it runs normally. Don't leave it like this, because it'll be louder than Hell. And also the possiblity exists that you'll get cabon monoxide into the cabin.
Gilly

Also check the distributor and rotor cap -- we had somewhat similar problems in a 190E (difficult to start and then dying while driving) and replacing the distributor and rotor cap fixed it.