Chrysler Repair: 96 LHS Power module, alfa romeo cars, primary coils

Question
Hi Roland, 96, LHS 3.5L motor, has new plugs wires and coil pack. Still get rough idle and code #43. Power Module sems to be bad, Right?
will replacing this probably cure the buggy? Nothing else wrong, has 197,000 miles. Please let me know if you need more info? I do the same sort of troubleshooting for Alfa Romeo cars to help club members or anybody.
Thank you, Mike Juneau

Answer
Hi Michael,
'96 was on the cusp of OBD-I to OBD-II diagnostic systems so it isn't exactly clear what a code 43 might mean. In OBD-I it meant that the pulse response on one of the 3 primary spark coil pack circuits is not responding with the correct time pattern. The test for that would be to check the resistance of the three primary coils (between the common 12V input and each of the 3 other contacts that are all part of the 4-pin plug socket) which should be 0.45 to 0.65 ohms. Then if that passes to verify the wires of the 3 coil primary contacts on the harness end of the plug to their respective pins at the PCM. But I recognize that you already replaced the coil pack.  
On the otherhand, the OBD-II system during its early years did allow for ignition key readout (which is what you are doing, correct?) and in that case the 43 code means either a single or multiple cylinder misfire detected (basically a rough idle!). That being a possibility, you are faced with the laundry list: primary or secondary ignition, fuel delivery (filter/injectors),observe vacuum gauge pattern shown by the the intake manifold/vacuum leak?, egr valve ajar, restricted intake or exhaust, PCM, mechanical issue with the engine...
So verify the primary coil harness wires to the PCM, then think about egr valve not being closed fully at idle (lubricate the stem inside the 'saddle', and test its movement with tip or screwdriver in slot of stem), then consider a vacuum leak at the manifold proper or its hose connectors; those would be my priorities. I would put the PCM low on my list.
I'd be interested to know what proves to be your solution.
I just got a note from an owner of a similar vehicle who found it to be an intake manifold gasket leak that produced the P0300 code, which is also the 43 code in the early OBD-II.
Roland
P.S. I am impressed by the challenge you must face in your "expert" activities. The literature available must be somewhat less voluminous that for domestic U.S. cars.