Sounds like the power brake booster is bad.
95 lin town car when turning on air conditioner and the clutch kicks on in the air compressor it jerks and the jerks at the same time car experiencing loss of electricity from engine when it jerks
This means when your car jerks very hard.
Not knowing exactly what they did my best educated guess would be that the idle is too high.
When an automatic car jerks into fourth gear it could be the transmission. You may need transmission fluid or a new transmission. A licensed mechanic can check the car.
Water in the gas
If car jerks around 70 miles per hour, the wheel may off balance. The axle or undercarriage may also have issues.
Something is wrong
Trans problem
Engine is in need of tuning.
no this will not ruin your car BUT it will start to scrape your gear because it is not being shifted properly
When the idle goes rough, you must idle the plugs. Else the car plugs roughly.