I have a 2002 Nissan Xterra with 250k miles on it and it runs like its was just off the factory floor, or at least it did. Today I got in my car and started it up normally and put it in drive to leave, but when I took my foot off the break it started to roll backwards on flat ground. I immediately put my foot on the break and looked to see if I might of put it in reverse by accident, but it was in drive. I took my foot off the break to see if it would do it again, but it didn’t. However the whole drive it didn’t respond the way it used to, it was more sluggish, but only slightly. And now it whistles in relation to the throttle that I never had before. Anybody have any idea?
When was the last time the transmission fluid was serviced?
Transmission shift linkage giving up?
You should get the whistle noise looked at , at least do that. Whistle-like sounds can indicate a vacuum hose leak, or some vacuum-actuated component is on the fritz. Any type of vacuum leak can lead to any number of drivability symptoms.
Sounds like it might be low on fluid or worn internal components. I would not drive the car without checking the level. If the level is OK, make an appointment. It may just be “giving up the ghost”.
A ‘whistle’ noise may also be a transmission that is low on fluid or that has a problem sucking air in the hydraulic system. I would have the transmission checked ASAP. Check the fluid yourself if you know how—the manual may describe the procedure. It is not the same as checking engine oil.