Additional information:

Car starts when cold normally with idle about 2000 rpm and after a few seconds it drops to about 1500 rpm until warmed up when it drops to about 800 rpm. However, if car is driven when cold, the rpm needle bounces erratically when at idle. You can feel the rpms changing. It has never done this before. Then it will gradually improve as the engine warms and the problem does not exist once engine is warmed up after several miles.