I had my 350z for a year now and have had a few problems. The Clutch needed to be replaced when I bought it I also had an overheating problem caused by a small leak. The car ran great for a while than randomly acted up. Some days ill put the key in the car upon turning on the car the RPMs would settle at 1,000 and I would begin to drive and it would go smoothly. Other times the RPMs would jump all over between 0-2000. When the car would hit zero the dash lights would come on like the car was off than the car would turn itself back on. The exhaust pipe would throw a lot of smoke ( more than normal since I usually always sow some because the catalytic converter is removed) One day it began to throw black smoke and a mechanic checked it and said it was the O2 sensor and fixed it and it ran fine for two months. Now again I am having the same problem with the RPMs jumping. When I come to complete stops the rpms drop to zero even with the clutch down. The right exhaust pipe throws out a lot of white smoke while the left throws a little. Also the left sometimes makes a popping noise. I was told it could be the Fuel pressure regulator. Can I get some input on what you guys think it could be? Thanks.

 

Start from the front and work your way back...clearly your reg is off, you need a scanner to check for codes...even if teh dash is not throwing any, smoke is not good obv and whether it is black or white does make a difference.