take a look at the rear of the firing pin. Is is mushroomed out? (espesialy at the bottom) This will cause the very rear of it to be too big to fit properly in to the hole in the slide. If so you could file/sand/grind off the protruding metal and watch it closely for further change, or call KT and have them send out a new FP (or both).
If not, then take an allen wrench (or something similar) and with the slide locked back push the firing pin forward from the rear. It should go forward smoothly, and go inside the slide a little before bottoming out. Also you should see the tip of the FP sticking out of the breach face. If this action is gritty or hangs up it could be your problem.
Have you ever taken the FP out to clean it and the hole it is in? Maybe it has finaly gummed up enough to slow the FP down...
check out the first part of this page for light strike help:
http://www.goldenloki.com/guns/keltec/prep2.htm
and also:
http://www.gunsmith.fuselier.com/lightstrikes.html
as far as upgrades, the only thing I know of that makes any real difference is the groove they started putting in the slide stop to retain the slidestop/assembly pin spring.
Here are a couple of pics of the upgraded slide stop for my P-32 with the groove in it next to the original without the groove:
here is where the spring rests in the groove when assembled:
if you need help taking it apart for the slide stop:
http://www.1bad69.com/keltec/disassembly.htm