Q: The car is driving jerky in speed after a vacuum pump was put in

I have had my car in and out of the shop for the past month. First time was for breaks, then another thing I cannot remember now, then this last time, (Friday) for a vacuum pump. Yesterday, when I would get below 55-50 mph to start slowing down, it would slow down very fast then speed back up very fast making the car drive extremely jerky. Then when I tried to slow down to stop it was like the car wasn't idling down or shifting down because I could feel it still inching forward with my foot all the way down on the break. What is wrong and how much may this cost to fix it? I've had issues with this car (too many to remember all) for the past 2 years that I've had it.

My car has 129000 miles.
My car has an automatic transmission.