I just purchased my first Maxima, not running at the time the guy I got it from had it at a dealer and they told him it was the fuel pump, I got it home and found that new plugs got it running but it loads up real bad at idle and up to about 3000 rpm, I can hold it at 3500 and above and it runs fine, and under a load it's all there also.
I also suspect the cats plugged due to excessive heat though floor board/consul, but would think that was caused by what ever the running problem is, any help would be appreciated as the local dealer already mis- diagnosed it.
Thanks, Dread

 

are you saying it's running horribly, horribly rich? If this were still the age of carburetors I'd say it was something stuck in the needle valve, but....
If it's giving it too much gas I suppose it could be a variety of things in the system (computer, oxygen sensors, airflow sensors, bad injectors, etc, etc). Is the car giving any error codes/ check engine light? How did each of the old plugs look? Were they all black and sooty or only some, etc. BTW, a book I have here says your cat's hot not because it's plugged, but because you've got unburned fuel going through it (so that's some good news )

PS, does anyone know if an injector can get stuck in such a way that it's just CONSTANTLY leaking gas into the intake port?