Sure, converting a dedicated former 220v range circuit down to 120v is definitely possible. You MUST make changes at the breaker box, do not simply change the outlet itself to a standard 120v outlet without changing from the current double pole breaker to a single pole breaker... you will burn out the entire electrical system/electronics of the new gas range! Some 240v circuits use only two wires and others use 3, If yours has 3, one wire should stay on the neutral bar in the panel and one wire to the new single pole breaker. the third wire will not be used anymore and can be curled up and capped inside the panel. If you have a 2 wire circuit, then detach both wires from the current 2 pole breaker and place one on the neutral bar and the other to the single pole breaker. When changing the outlet in the kitchen, the color of the wire (usually red or black) that you have attached to the single pole breaker will go to the brass colored screw on the new 120v outlet and the wire you have attached to the neutral bar (usually white) should go on the silver screw of the 120v outlet. The wire you capped in the panel will also be capped in the outlet box since it is now "dead".
Now for location...if the existing outlet if fed from below and you will be moving it lower to the floor, you should be fine since you will have enough slack in the wires, however if the opposite is the case you more than likely will need to run new wires. Good luck.

Let me clarifiy something that Scotty says, when he's talking two versus three wires he is not counting the bare or green wire which is the equipment ground. That stays as it is (and connected to the green screw on the new receptacle).

If you have the two wire scenario described above, please mark both ends of the wire you make into the neutral white.

In many panels that are at the main disconnect, there may not be a separate neutral bar (look for where other white wires are connected).

Add on more thing... the wires used for stove wiring will not fit a 120V receptacle, you must pigtail some 12ga wire to each wire in order to fit the receptacle screws. You may have to do the same at the breaker end also, depending on the type and design of the breaker.

And if the existing wiring is aluminum, you'll need to use a rated splicing method.

I know this thread is twelve years old. :) I have a standard single-phase system. My existing dryer outlet was 240v and has a three-wire (red, black and white) with bare wire ground going to a double gain circuit breaker. Dryer is an old Miele and has a four-prong plug. I am putting in a new dryer that takes 120 and I did not want to run a new wire all the way from the breaker. I replaced the double gang breaker with a single gain breaker (AFCI and GFCI breaker since I was in there) and capped off (with wire nut and tape) both ends of the red wire. I have 120 at the outlet. So far, so good. With circuit live, i am getting about 25v on the completely unconnected red wire. Is that from a magnetic field from the still connected black hot lead? Red wire is capped and the two ends are in the fuse box and outlet box, so seems safe. Anyone have any safety concerns about this? Many thanks.