Ignition just cuts out.

Help i have been stranded twice. Cruising down the road at 2500 rpm, after car gets warm, when all of a sudden igignition just dies, then it is real hard to start, and sometimes it just cranks with no spark. When you do get it started it will only run a short time. When you try to start it and let off the key, it kind of trys to start. I have the FBO ignition on it, and have had no touble for 6 yrs. It is a 69 B-Cuda with a 340. Have tried diferent ECU, coil, and ballast resister, still does it. coud it be the coil pick up in the distributer,??.

Barracudadave67