Cr*p, Engine Problems?

Hello All:

I'm hoping that someone/anyone can help me diagnose my Automatic '98 V-6. It's got 106k and is my daily driver. Recently I noticed the engine "missing". Now I'm starting to notice almost ZERO acceleration when mashing the pedal to the floor. Correction sporadically (more often than not) I am noticing this. Would just needing new plugs cause this? My injectors should be fine, I run Chevron Fuel Injector Cleaner through a tank every 5k. About 6 months ago I cleaned and re-oiled my K&N air filter, so there should be no airflow problems. MAS? Possible change in climate now that WA. is getting a little more sun than rain (ie air not as dense with cold air from rain)? I am also noticing that when I go to accelerate real quickly then let up it sometimes feels like the car (? transmission) "misses" - kinda lurches forward and or steps down a gear too quickly. It used to do this smoothly before. I hope that makes sense. No sounds heard to speak of. Possible belt maybe? Please forgive me if my input seems laughable as I am not too mechanically inclined.

I thank you for any help that you can provide.

Just a quick follow up to this story. I took out the old autolite platinum plus 4's I had in there and they were toast. I'm sure these were the problem. Three of the 6 have carbon build up on them and on two one of the prongs must've gotten superheated and almost collapsed onto the ceramic! Anywho, it looks like it's working fine now. THANK YOU to all who assisted me with this thread.