KevinW

My hunch is they are only effective under extreme conditions and might serve to forestall ABS intervention.

I believe the 1996 model year is quite unique for the DeVille, as it may be the only one in which the entire production were originally equipped with electrically adjustable dampers. Standard models were equipped with RSS (2 position dampers) and the Concours was fitted with CVRSS (continuously variable dampers - first year).

If the injectors came from an '85 RWD model, they're for an HT4100. The '86 RWD had a carbureted Olds V8. The inductive timing light shows there's some current in the ignition wires, but it doesn't mean a spark is occurring in the combustion chamber. The ignition energy will find the easiest path to ground, which could be the carbon coating on the insulator. You should clean the plugs thoroughly or install a new set. Did you test the MAP by direct measurements or did you monitor the ECM data via the OBD? If all the inputs are correct, the fault may be in the ECM hardware. A used one should be inexpensive; remember to transfer the Memcal/Calpak.

Sounds like sitting overnight helped to clear a flood condition. Are the plugs still covered in carbon? It's possible an ECM driver problem is affecting one injector. How does the spray look under a strobe light?