Q: Car won't accelerate randomly when sitting in traffic, no change in engine performance, just won't go for 3 to 4 seconds

There was a Nissan recall in 2009 for your model year (2006) relative to an air intake fault. Be sure your vehicle was either not included in the recall or, if included, that it was serviced as this particular recall could have some bearing on the issue you are describing. To determine if your vehicle was recalled you can give your VIN number to a Nissan dealer and/or input your VIN at the NHTSA website. No engine response to throttle (accelerator pedal) inputs points to either a throttle body fault (throttle position sensor, mass airflow sensor) or a fault in other engine sensors that rely on a signal from those components. An automotive scanner that can report real time engine operating parameters would typically be used to narrow the diagnostic. If you desire a mobile diagnostic, as well as any required repairs, please use YourMechanic’s engine loss of power diagnostic service request page. If you request that diagnostic, the certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.