My car has been running like a dream ..... idles as smooth as can be and instantaneous response to the throttle as well.

This morning however, as I approached work it suddenly began to jerk and idle as though something was amiss big time!

I came home and checked all the vacum pipes, especially the one under the air cleaner and all was fine. The pipe that comes out of the valve cover into the air cleaner was a little loose, I tightened that. Air filter is good (newish) and fuel is full - premium.

After all that - still idles like a beast. The car shakes tremendously and for the life of me cannot figure what went wrong!

New wires (beru), plugs, distributor and rotor and cap. New starter, new run insurance ...... new meaning less than a year old.
Fuel Inj cleaner (Redline) with every oil change ......

Thoughts as to what this can be??????