There are no lifters in the overhead cam modular. There are lash adjusters but they shouldn't be bad.
If you're getting a misfire the first thing I would do is check your wiring and swap the #2 COP with another cylinder's COP. If it follows there is your issue. Also did when you did the plugs did you gap them properly and torque them in to spec?
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.