That's very likely the cause of the reduced power. If the plugs are worn along with cracked coils that will cause a weak spark. And a weak spark can also cause pinging. Once the pinging starts the knock sensor will detect it and send that signal to the ECM. The ECM will then retard the timing to minimize the pinging. Weak spark + retarded timing = reduced power and lousy acceleration.

1998 Sportage - Gone.
2004 Honda Civic Coupe.
2007 Suzuki Grand Vitara - She got it.