Help with misfire codes on 97 960

[mechanye]

97 volvo 960 with 150,000 miles. Started idling rough with p0302 code.

I swapped coils around and still had same code. So i swapped the ignition control models around and then got a p0305 code.
This made me believe that the Ignition control module was bad. I replace the module and I still get the p0302 code with the new module and if i swap it with the other one then I get the p0305 again. What is the chances that the new part would be bad causing the same cylinders to missfire? Vehicle runs fine at higher rpm. Any suggestions?