I have a 98 Camaro 3.8 v6 auto transmission. I just had the plugs and wires changed and now I am getting a P300 error message on the scanner indicating misfire. I checked all the wiring and made sure it was correct. Should I have had the ignition coil replaced along with the wires?

 

Is the code just there or is it running. I dont know what your scanner is capable of because it could be a memory code. Also drive for about 25 miles to clear the monitors.
Also OBDII will compensate very well for a problem. Check and make sure all your plug wires snaped on good. I had started a 96 Astro van and forgot to put on 3 of the 6 wire and the damn thing ran. Ran rough but it did run.