Possible speed sensor gone bad

Since roughly January of 2019 my car has been rough on shifting and basically wanting to go the speed it wants to go. If I'm going down one of my main highway it'll take me about 1/4 of a miles to get up to 55 mph and the rpm's aren't correct. I just noticed a couple weeks ago that when I got the cruise control button the light will turn on but the car with not set a speed. At first I was thinking the transmission was going out but now I'm wondering about the speed sensor. My speedometer works but my gas gauge doesn't all the time. Back when this first started happening my ABS light would come on the words anti-lock system failure would display. If I put on the brakes the car would shut off if I didn't double pedal it. I'm looking at buying a different car today and just came across the information about the speed sensor and had to ask.