Chrysler Repair: Chrysler misfires, powertrain control module, spark coil

Question
I have a 1997 Town and Country. There was a gas leak which required the fuel rails to be changed. The shop then thoroughly cleaned the outside of the engine. Ever since it has a rough idle and rough when just starting at low rpm, like it is misfiring. I have taken it back twice. The mechanic told me the code was for the coil, he checked the wires, said it ran fine. Well he is in denial it still misfires. I am fed up with him. I checked the codes as you have told us and got 12, 43, 55.
I will take it somewhere else. Do you have any ideas as to what it is and how complex?

Answer
Hi Randal,
The code does mean that one (or more?) or the three circuits that activates the primary winding(s) of the spark coil pack is not responding properly which suggests to the controller that either a coil or a wire in the harness between the controller and the coil, or the controller itself is at fault. So you check the coils and the harness, and also just on a chance make sure that there is 12V coming to the the other end of the coils from the autoshutdown relay, and if those three parts of the primary circuit test o.k. then the conclusion is that the controller itself is bad.
So if you have a digital volt-ohmmeter I can tell you how to use it to check the coils and the harness and the ASD voltage to see if you can conclude which part needs to be replaced. You might want to disconnect the battery for a minute or so to erase the 43 code, and then see if it comes back again rightaway.
If the mechanic only checked the  continuity of the wires in the harness without also checking the coil resistances, he may have missed something. Or maybe he didn't check for a short circuit in the harness for example. So if the 43 code is valid, it isn't a big deal to test and decide whether to invest in a new spark coil pack, a new harness, of a replacement powertrain control module. This problem could have happened during the cleaning process which might have left some water in the plug connector for the coil pack or at one of the 6 spark wire towers of the pack, so those would be good to look at and dry out if you find any that are wet.
So let me know if you have that type of meter or not and if you want detail on doing the checks. Also tell me which engine is in the van.
Roland