As said before, boring out a cylinder will not change anything on the PCM. It will slightly lower the CR due to the cylinder being slightly larger but nothing noticeable IMO. But thats assuming you are using the same CC'ed pistons.

Will not make for a noticeable difference (especially at .020).

.020 bore will only give you about 3-4 more cubic inches on a 4.7L engine. This means only about 3-4 more horsepower, all things being the same. No PCM programming is not required for that small of change.