explorer problem when backing up

the other day i was backing up my mom's 2000 explorer xlt out of the garage. when i put it in reverse, it inched backwards, then "jumped" like it was changing gears, and started backing up smoothly, and everything was normal after that. Now every time we back it out this happens. By the way, its the 4.0 SOHC V6.
Any help would be greatly appreciated.

if it is 4wd, then it could possibly be the transfer case catching on when gears are changed from park to reverse. try holding your foot down on the brake as you back up, and just ease it back, then see if it happens. if that dont work then, um........hey i think we need some more replies and input from people.

If the truck is 4x4 all the time it is possible that the tires (frt and Rear) are different size or maybe a bad sensor(2 of them). The problem with 4x4 all the time is it runs on sensors and if there is a slight difference in the tire size(even due to wear) it will effect the gear changing. My 4xx does this on icy roard when the rear tires go slightly faster.

Another thing is that when you put it in R, you need to wait a second and it'll fully shift, then back out smoothly. I think you're just lettin off the brake too soon.