Alright, heres what has happened.

1: Installed kooks longtube headers and tsp true duals(no rear o2 sensors no egr or air)(replaced plugs/wires in process)
2: Installed ls6 intake manifold(got rid of that egr)
3: took out entire AIR setup
4: noticed shifter shaking a LOT, so i mentioned it to ls1tech and got the advice to check each cylinder
5: did this and found out rear most driver side cylinder not firing
6: checked wire and wasnt firing, tried wire with another coil pack and was fine
7: father removed coil pack and we're gunna check it with a multimeter tomarrow

Conclusion: If the coil pack comes back fine what do you suggest doing? Also is there a reason that this might have happened, need advice bad!

 

Check the plug on that cylinder.

 

Carefully check the connectors, people commonly get the pins misaligned. Check for spark by inserting a screwdriver into the wire, hold it 1/4 inch from ground and start it up. If you have spark, replace that plug.

 

Just swap the coil you think is bad for one from a different cylinder real quick and see if the problem follows the one. Just plig it in, dont bolt it down. I have ohmed bad coils that showed OK on both the primary and secondary windings.