Yes That would be the air filter most likely
where is water pump located
its located under the engine cover in between the heads
yes.
Lower rear of engine on passenger side
slightly to the left of the throttle body towards the front of the engine
Front of engine---r/s underhood
In the front right of the engine, and under the rear seat.
between engine and firewall left side
need vacuum diagrams(engine)for 1978 cadillac deville
The oxygen sensor in a 1988 Cadillac Deville is located in the exhaust manifold. It constantly monitors oxygen levels in the exhaust to allow the engine to operate and peek efficiency.
If it is the Northstar engine which I believe it is, it is inside the motor under the intake manifold.
The 1997 Cadillac Deville fuel pressure regulator can be found on top of the engine. The fuel pressure regulator will be near the fuel injector pump.