Fluctuating speedometer with no check engine light

Don't get mad at me if it has been buried but I've been searching around the threads and cant find my issue. So recently I had my "check emissions system" light come on due to a loose pcv hose, when this happened I also noticed that my speedometer wasn't functioning properly. I fixed the issue with the hose and the light went away but now I'm left with my speedometer still fluctuating, when I drive my car and shift gears it drops 2-5mph and bogs sometimes, also when I let go of the accelerator it will fluctuate from about 40mph to 20mph then 0mph. I've been trying to research this problem and seems to be the speed sensor from the little information that I could find. I'm not too knowledgeable mechanically but know enough to replace and fix issues that I've come across before. I cant find a video or thread on the speed sensor that would cause this issue, not too sure if its the abs speed sensors but read that it would be on the transmission. How would I know which sensor to do voltage/resistance checks on? I don't know the speed sensor locations and need some help if anyone is able to offer any advice.