First time posting on this forum. I have a 98’ XJ8 that recently had a complete transmission rebuild. Over the past couple weeks of driving I’ve noticed some things. Whenever I put the car in drive, it jerks forward pretty hard. Other things I’ve noticed are that it’s acceleration uphills and its acceleration in general are extremely slow compared to when the old transmission was working. Not sure what the problem could be, maybe the mechanic messed something up?

 

I too had a initial harsh shift into drive following my rebuild. Mine turned out to be a fouled temp. sensor in the transmission. Definitely take it back to whomever did your rebuild .