Hello I have a 1993 Toyota Corolla and it has been running rough at idle and very low speeds. So far i have replaced the spark plugs (each of them had a grove worn into the center electrode) replacing them helped, however the car is still shaking quite a bit. It is only rough when it is in gear.
Did you change out the plug wires along with the plugs? If they’re original, it’s definitely time. If this car has a distributor cap, replace it and the rotor as well.
I replaced the wires 2 years ago and the distributor and the rotor 6 years ago, however the ignition coil has never been replaced.
Are you sure there was a groove worn in each of the electrodes? Or were these perhaps NGK V-Power plugs? Not a helpful question, but just curious.
Haha your right they were that makes sense now. Oh well they are gone now 
. I should add that i feel most of the vibration in the steering wheel.