94 Accord, Auto Transmission, 151k mi

Past few days, my car has cut out suddenly when traveling on roads with 40-55mph speed limits. It generally happens when I am coasting, foot is off the gas pedal. I notice erratic jumping of the RPM gauge and then it fails. Generally it has not been a problem to stop, place in Park and start the car again, but today it took a few minutes before it would start again.

I checked the codes, it's throwing 15 "Ignition Output Signal" -- most searches I've done are generally with folks who can't start their cars, this is while driving.

Any help is appreciated!! Thanks

 

Any thoughts? Anyone else have this experience? Also, this is a 4 cylinder engine. Thanks