Hesitates

First if the problem seems to be that the transmission is, "slipping" in reverse but not other gears, there is an internal problem with the transmission. Now the fact that forward or drive has started to do this as well indicates some internal problem that would probably require a rebuild. Possibilities could be eliminated as to electronic control issues by having trouble codes scanned. This can be done at any Auto Zone or Advance Auto for free.
If I mis-understood and the hesitation is related to engine performance, the same trouble code reading will give you some direction into the cause of the problem and will be the best way to see if it may be connected to the repair.
Anytime a vehicle is repaired the possibility of damaging other parts or leaving something unhooked, like a vacuum line that was not re-attached, could be something that just happened and it is not necassarliy a sign of poor workmanship, just a mishap.
To go over the possibilities of hesitation related to engine performance, however the reverse gear being the major hesitation made me think you were talking about a transmission related problem, I am giving you a link to a walk through diagnostic on engine hesitation issues.

Here is the link;

https://www.2carpros.com/articles/engine-hesitates

Do you have a check engine light and when was last tune-up?

Have the fuel pressure checked if its within specs, check the transmission fluid level and condition-to me it seems like the transmission is slipping, bring it in and have it further checked out-

Go to this link for more information: https://www.2carpros.com/articles/engine-hesitates

Matlock, did that link give you the information you needed to fix your vehicle?

You hit the nail on the head. Try cleaning sensor with cleaner before replacing it. But you might need to replace it.