There are lots of possibilities which would take a long time to go into to, but here are a few all harness related cause the harnesses suck

-Bad or coroded injector connection
-bad or coroded coil pack connection
-bad or coroded ignitor harness conection (passenger side of the front engine cover)
-bad or coroded cam angle sensor connector(driver side of the front engine cover)

Try wiggling all these connections. Also pull off coil pack plugs one at a time to see if it is one(or two) specific cylinder that isnt firing

If you cant figure it out, feel free to give us a call and we can check it out