Had code p0340 changed cam shaft sensor still have hard start and code on 2005 Nissan Sentra 1.8?

I had the same problem. I havea 2005 Nissan Sentra, started throwing the code, bogging out, hard start. Replaced the sensor and cleared the code. Worked for a couple days then started doing the same old crap. Replaced sensor again, thinking it could be bad, (under warranty,AutoZone) and still, no better. It's not all the time, just randomly, and it drives me nuts!!! I took it to Nissan one day, and asked them, and the arrogant prick (without even looking at it) says it's probably the crankshaft sensor not the camshaft throwing the code, and it'd be $260 approx. to fix it.

Screw him. So in the meantime, I just carry a 10mm socket wherever I go, and just undo the sensor plug, wait a min, start it back up, wait for it to not idle crazy, let it sit at 1000rpms, and if the tach doesnt fluctate, I'm good. So, saving the money for now, doing more research. :)

(Oh, and I'm a girl btw...and I always do my own work on my cars, and all of them have gone WELL over 300k miles, and still ran great when I sold them...just sayin'... ;)