99 jeep

years ago when car had points i was an auto mechanic so i like to think i know a little however my jeep has a transmision problem if i pull out slowly it shifts up and back down as i know it should not do. it does not slip yet any way years ago i would have sovled this by changing the vacum modulator but having already been under the car i do not see one i am guessing these are now electronic if so are they something i can change myself or not.

I have seen a few Jeeps with faulty TPS sensors causing this problem. Is this a Jeep Cherokee?