Plymouth

If the Check Engine light is on, start by having the diagnostic fault codes read. If it comes up with "Cam and crank sync", first check the timing belt. At one tooth off, the Check Engine light will turn on. At two teeth off, the engine will shut down and typically one ignition coil will fire intermittently. At three teeth off, the open valves will hit the pistons as they coast to a stop. If the belt timing is correct, suspect a sheared-off dowel pin between the camshaft and its sprocket. This applies to the single overhead cam engine, not the dual cam engine.

Caradiodoc

If you can borrow a Chrysler DRB3 scanner, it will let you fire the coils. That will show whether the Engine Computer has control of them and that the driver circuits are working. The fact there are no codes means the problem is with something that isn't monitored such as the coil secondary or the conditions needed to set the codes hasn't been met. Since you already replaced the coil, I guess I'd be considering a different computer. You could also look at the wire between the computer and coil. A corroded pin in a connector or a cut wire are possibilities. You also might try using an oscilloscope to view the signal on that wire. If there is none, view the waveforms coming from the cam and crank sensors.

Caradiodoc