s13 cruise control acting up

[todd5854]

Stock KA... swapped it manual, and there was a relay I was told to remove and jumper to get the cruise control to work again. I found 5 different guides, and they all said to jumper the same one, so that's what I did. Worked fine for the first two months

Now, when I turn it on, lets say im doing 70... if i press "set" it drops to 65. and maintains it for a little while. If I press and hold accel, no matter what it will accelerate to 70 and no more. if I hold it until it reaches 70 and then let go, it still drops to 65.

I checked where it connects to the throttle body, there is a nice tight cable connected..

My first thought is the vacuum pump / diaphragm is going bad. does that borrow vacuum from the cars system? Or does it use its own? hopefully its own....