I went out to my XJ this morning and it started as usual, I backed out of the parking spot without issue, but after putting it into drive and pulling forward, it took a great deal of throttle to get it moving. I drove it 30 minutes to work on the Interstate and it cruised at 65, but still seemed to be lacking any get-up-and-go. After arriving to work I tried backing it up in the parking lot and it chirped the tires, but in any forward gear it felt as though something was holding it back. The emergency brake was disengaged and the automatic transmission fluid was within normal range. I have had no issues with the transmission slipping in the past.

 

I think your E-brake may be locked up, happened to me on an old xj I used to have. Also, make sure you're not in 4wd or your diff's unlocked, I might be WAY off,lol, but that's what I'd check first.