Well, I have the same noise when accelerating...Nissan tech said I should try a tank of 93 octane and see if it gets better..I have been puting 87 octane in since purchased (10/99). Just filled up with high octane...so I will post again with results!

BTW: I just had my 60k service...clean throttle body, spark plugs, (recently put on new plug wires) and it still does it! Tech did say after cleaning throttle body, there was some carbon build up that could adversely affect performance.

What octane do you use?