Note on Intermittents
WARNING: This page is about a different car, the 1990 Cadillac Fleetwood and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
If Code E12 is stored as a hard code, start engine and allow to idle while manipulating circuits No. 430 and No. 453. An intermittent open will cause the engine to stumble or quit when ECM loses distributor reference. If wiring and ECM connectors are okay, check HEI pick-up coil leads for intermittent open circuit.