In a recent mod I made I converted Mobile Sams to air units to enable it to intercept Bombers...the problem is it still maneuvers and can actually move over water. My question is how do I adjust it so that it cannot move over land (or water)and only from city to city similiar to bombers and fighters?

one flag: immobile
one command: rebase

Of course, it can still have other flags and commands, but those are the two bits you need.

one flag: immobile
one command: rebase

Of course, it can still have other flags and commands, but those are the two bits you need.
this will not work.

you'll need to flag it w/ the "intercept" flag (assuming you keep it as an air unit) and give it 0 (zero) range.

why not just add in interceptors and leave the SAM as a land-based unit?

In a recent mod I made I converted Mobile Sams to air units to enable it to intercept Bombers...

Wouldn't that mean he already set it with Air Superiority and 0 range?