Hi, I have a Acura 2007 TL. recently, when I speed up to 70km/h (I am from Canada) then slow down naturally (no control to break and accelerator), every time reach to 50km/h the tachometer suddenly bounces from 2k to 5k then drop back to 2k. same issues happen when reaching to 30 and 20km/h.

Please help to figure out what kind of problems in my car. Thanks a ton in advance.

More details about my TL:
mileage (KM): 160k

 

Does the car's engine RPM change when the tach bounces from 2k to 5k and back, or is the tach needle bouncing without a change in engine RPM?

Welcome to AZ.