went to go smog my car today, but they wouldnt do it cuz i had no carb sticker for my engine intake ( even though i know its carb legal) so i swapped it out with my buddys stock intake, and took it back....well apparently it failed while it was there, cuz the CEL came on, and they got p0300 code and p0550... i know that the 550 is my power steering pressure switch....but the p0300 is kinda out of nowhere...it showed up a few months ago but went away after a day....any ideas? i have a week to figure this out and go for my second chance to pass smog....its a 2003 enthusiast.....only other mod is a borla muffler.....i did notice a rough idle....and loss of power alot of the time....and yes i did search the forums for this code and also googled it...i came up with possibly a crank sensor malfuntion, but im not getting that code, maybe sparks, or coils, or spark plug lines, .....not sure really though, any help would be great cuz im bout to leave on deployment, and really cant afford to deal with this right now thank you guys

 

http://www.nissanhelp.com/diy/obd_codes/p0300.htm

 

^ sounds like:
•Intake air leak

 

http://www.nicoclub.com/archives/350z-ecu-codes.html
random misfire. Give the car a tune up

 

car is well maintained...just changed oil on engine and trans along with a radiator flush, and all new other fluids....i will check the air intake to see if its put on correctly...i cleared the code yesterday...then drove it around for 10 mins at 2500 rpm (65mph) and light didnt come on so i then drove at at about 80 mph for another 10 min...no light...so im wondering if it was just a intermittent issue