ya,it was the ballast resistor. thanks all.

Now, get two, and carry the spare in your glove box. Those can go without warning, and leave you stranded in the convenience store lot on the way to work.

Roger

Just to follow up, the guys were dead on, I've had this exact issue both with the ballast resistor and ignition switch. The latter time a thin piece of sheet metal from earlier work had fallen onto the contacts of the ignition switch and shorted it somehow...it would start and then immediately die. Got under the dash with a flash light, pulled it out, fired right up....

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https://tinyurl.com/yynpj4v2

BTW if this is a stock Mopar ignition (points or ECU), get either the BWD RU19 ballast (1+ ohms cold) or, better yet, a NOS 2095501 ballast (.5 to.6 ohms cold) or an MSD (.8 ohms cold) ballast.

There are a bunch of ballast values around (some that have round mounting tabs) that have significantly higher resistance (2 ohms cold and 7 ohms hot) than the original, and that will starve the coil of proper current.

I am beginning to suspect that the wrong ballast resistance has made more poor running Mopars than you can shake a stick at.