Hope you didn't use anti-seize, the newer plugs are meant to not have it for consistent torque values when you put them in.
My LR3 was feeling a bit sluggish...
That sounds made up. Can you cite a source on this?
More than likely your injectors are partially clogged. I would have them flushed or try some fuel additive. While I have never tried it, I have some friends that have had good success with BG 44k in the tank to cure lean faults caused by clogged injectors.
http://jenniskens.livedsl.nl/Technical/Tips/Files/Sparkplug%20NGK%20TB-0630111antisieze.pdf
Posted this before back when I changed mine out.
I actually ran some BG 44k through the tank about a year ago, but I couldn't notice any discernible improvements at the time. These new plugs definitely improved the pickup.
http://jenniskens.livedsl.nl/Technical/Tips/Files/Sparkplug%20NGK%20TB-0630111antisieze.pdf
Posted this before back when I changed mine out.