2000 Maxima GLE Idles fine in gear but dies in park?

I have a 2000 Maxima 3.0 L V6 w/ 163000 miles on it. The problems I am having are that I have to let it warm up quite a whie before driving off because it will jerk and sputer and feel almost like the trans is slipping. It will also idle fine in gear after warming up but about 15-30 seconds after I put it in park it will die! And while coming to a stop at night with the lights on I notice a slight blink or quick dimming of the headlights when the car downshifts. Over the past year I have replaced the altenator, starter, battery and a couple of the ignition modules. I related those all just to normal wear and tear except for the ignition modules (I understand that is an inherant problem with this make/model). I have also kept regular oil changes a must and been good about all other maint. I also have changed the the trans fluid/filter and it still is all happening. I have also in the last year replaced two of the O2 sensors since the check engine code indicated that was the problem!Before I replaced the battery it would idle wildly up and down in drive but that problem stopped after battery replacement. I have not had anymore check engine lights since the O2 sensors were replaced but it still acts up. After reading some other posts i'm begining to think it may be a fuel delivery or mixture problem since the cat converter also smells horrible, either that or it is possesed. HUH! Other than all of that it is a pretty good car! ANY help is appreciated!