I have a 2000 Max with the 5-speed that occasionally slips out of fourth gear. This problem first occurred about 3k miles. I took it in the dealer, but was unable to reproduce the problem. I went on vacation, letting the car sit for 10 days, afterward the problem seemed to disappear. Recently, with 35k miles, the problem reoccurred.

It will only slip out when it is fully warmed up, usually after 20-30 minutes of highway driving. Usually I notice it after a tollbooth, when I am accelerating back to highway speeds. The range of speeds this happens is 45-70 mph, covering the full range of 4th (at least with my driving). It always happens when I have my foot on the pedal, never when coasting or braking. I do notice that in all gears, the shift lever moves slightly under acceleration. I would expect this behavior. The frequency of the problem is usually once or twice per hour.

Another dealer checked out the problem, but could not verify. He did a data base check to see if this problem has occurred in any other car, but none was found.

Does anyone else have this problem? I am sure I will eventually get the dealer to verify, and probably get a rebuild, but I do wonder how I could be the only one with this defect.

This must be either a manufacturing or a part tolerance defect. If I were a Nissan engineer responsible for these transmissions, I would do whatever I could to get my hands on this individual transmission. Very infrequent failures are nearly impossible to troubleshoot if you don't have a 'smoking gun' example.