My car had a very short (1/4 second) stumble in the idle immediately at startup. Other than that the idle was very smooth.

He said I needed new plugs. Fine. He changed them.

NOW, it won't start unless I give it gas. If it does, it runs very rough and won't smooth out until I give it gas. Even then, it runs rough.

What could it be?

[He said that before long I'd need a new distributor cap, rotor, O2 sensor, and wires.] Maybe, but with the current ones it was running very smoothly, now it isn't.

Yes, I checked. All the wires are securely attached to the plugs.

This is a MB-only, certified tech.

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1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles