STUPID QUESTION. But I must ask..
Did you check the plug firing order?
If you picked it up this way, It could happen.
It sounds like it's barely driving..

 

I did and the aftermarket coil pack had the cylinder labeled on it where to plug it in. as did the one that i took off. The coil had 5,1,3 on the top and 6,2,4 on the bottom if you were to look at while it is mounted to the intake. so I plugged the wires back on in the order it had.