Transmission jerks and lurches into all gears. Problem started without any prior warning, one day fine, the next rough shifting.
Is the check engine light on? How many miles on the car? Has the transmission fluid ever been changed?
No engine light. 86K on speedo. Fluid has never been changed.
I would suggest that changing the trans fluid and filter would be a good place to start. Possibly a bit of debris in the transmssion broke free and is plugging an orifice.
Agree that’s the cheapest place to start , change the tranny fluid .
This car is due for its third fluid and filter change at this point. However, the OP should be sure to AVOID chain-run places like Lee Myles, Cottman, Mr. Transmission, or–God forbid–AAMCO for that service. If he goes to one of those places, he will be told that he needs a new/overhauled transmission–whether he does or not.
A well-reputed independent mechanic’s shop can do this for the OP, and is likely to provide that service at a fair price.
As posted above, there are many small openings and tubes for the fluid paths inside an automatic. It’s sort of alike a computer but instead of wires it uses tubes containing transmission fluid. Those paths, however small they are, must remain open. If a bit of debris in the fluid finds its way to one of those tubes and clogs it, this could be the symptom. You’d notice an immediate & adverse change in performance.
Don’t get a flush, get a pan drop/filter replace. Many a vehicle transmission with mileage like yours has gone belly up after getting a flush. Too much new fluid at once. Sudden rough shifting could just be a shift solenoid. Very cheap easy parts to replace on GM RWD tranny, not sure about FoMoCo.