97 bonne problems
 

3.8 non-supercharged 103K. Plugs, wires, all coil packs replaced, fuel filter, air filter, intake leak, injectors cleaned 6 months ago. The MIL light has been coming on and off for some time. Runs rough or starts rough at a low idle. I get P0305 cyl 5 misfire and P0171 system to lean bank 1. What can I do to fix these issues? I just got a Actron CP9180 scan tool to get the codes.

Any help?

Does it run fine at higher rpm? If it only misses at an idle you have a mixture problem. The upper intakes and gaskets are known to be bad on this engine. I would do an injector balance to see if the #5 injector is not flowing as much fuel as the rest. Also a quick check to see of the plugs are bad is to swap two of them, if the miss moves to another cyl. the plug is bad. You can also do it with the wires.

The car does run OK at high rpms. I will check tonight to see how the plugs are wires are.

If it runs ok at high rpm, then the plugs and wires are probably ok. It has to be a mixture problem. While it is idling, spray brake or carb cleaner around the intake to see if rpm changes. If it does, then there is a vacuum leak at the intake. I think that the injector could be bad.