Just bought a z28 Camaro and it started missing real bad when the rpms got over 2000. I took it to the shop and they said I just needed a tune up so he replaced the distributor cap, water pump all the plugs and wires and it still ran bad once it warmed up. I have also replaced the maf, icm, had the pcm reprogrammed. When it goes to missing it does it on both the open and closed loop system also it is missing on the number 7 cylinder...... don't know what else to try any suggestions would be helpful

 

Could be a bad fuel injector. Swap the #7 injector with the one from another cylinder, and see if the misfire follows the injector. Valve problem.... adjustment came loose? Compression problem?

Since you know it's missing on #7, I assume you had it scanned. No other codes?