1996 Express Trans slipping

I had the codes checked and the guy said I had a trans sensor bad or going bad. Could this be why the trans. started slipping? This is a 5.7L 1996. I have no experience with type of vehicle and I want to try and figure out if I have a big problem or maybe an inexpensive fix. Thanks for your help in advance!!! Ron

There Are Two Sensors On The Back Of The Valvebody Under The Pan. Replace Both Of Them But Be Careful Cause The Valves Are Spring-loaded.

My 99' express Van its started to sliping shifting from 1st to 2nd at lower revolutions the codes that shows are 161 and 1870 it was repaired couple weeks ago but they use a refurbished turbine and the disc inside were changed but stills having the same problem

Thank You

I took to the shop again the problem wasn't fixed at all, although it works fine its start to slipping after a short trip in the highway, with speed over 50mph, when arrive to a reduce speed area like stop sign its start again shifting abruptly from 1st to 2nd and 2nd to 3rd and when i speed up faster (i usually speed up very slowly trying to protect te gearbox) but when i speed up faster the abrupt shift seems to be softer and i think the computer show the same codes again, any help so far? thanks