Hello - new to the forum. I Have a 1976 Eldorado EFI that was running perfectly until a couple of weeks ago. When warmed up, it would miss, hesitate, actually shook the car because of running so badly. Now it is doing all of that from a cold start as well (seems to have "evolved"). I changed the plugs. The wires are fairly new (when I bought the car). Once the part is delivered, I will change the fuel filter, but I do not believe that is the issue. Any recommendations?

 

Find a Genuine GM service manual.

The various sensors are critical to the operation of the fuel injection. That car is old enough that almost anything could cause problems--coolant temp sensor, manifold vacuum sensor, throttle position sensor, faulty wiring or corroded connectors, faulty circuitry within the computer.

Or it could be as simple as a failed distributor cap/rotor, faulty ignition coil, burned valve--all sorts of non-computer/non-fuel injection systems.

The usual advice when the vehicles were new was to verify all the non-fuel-injection stuff before diving into the F. I.