Rough Idle while stopped

I am looking to buy my 16 yr old daughters first car and I just looked at a 1996 Kia Sportage 141,000, automatic, 4wd. The problem that I incountered was when I came to a stop or just put in in drive or reverse with foot on the brake the car idled rough, Driving and in park/nuetrual idled fine. Car was idling around 800 rpm's according to the dash gauge which I know is not accurate but it did not sound to high/low to me and sticker under hood said 700-870 rpm. No check engine light on
So I was thinking it maybe the Brake Booster but not sure? and thought I would ask people who have worked on Kia's, And do you think a Kia Sportage is a good first car we need 4wd because it does snow where we live
They are wanting $2,400. I wished that Sacramento had hills to test the car on because we live up in the foothills I was just woundering how that little 4cyl will do.seem to have a lot of peap on flat roads

I feel tnat 2400$ is a little high.
Main problem with this car is corrosion...the metal alloy used is rather poor but you might be saved in your area because salt is not used by the tons like here in my northern area. I see pictures of 10-15YO Sportage in the south that I would like to buy .
Mine (2000) is pityful now....and all tubing underneath ..fuel, brakes...power steering and transmission cooler lines...had to be replaced for corrosion....and fuel tank too.
THe little car is fun and agile, not really powerful ...really not a dragster....

NOt too sure about that rough idling issue....since it occurs, seemingly, only in the condition you describe...and not during acceleration ..which I would have blamed on ignition, a common issue with this engine...EGR (exhaust gas recirculaton) valve could explain (by analogy with other cars I have/had) but it has been rarely an issue throughout the Sportage forums....honest..I even wonder where it it.....
....others might come with other suggestions and maybe more questions.

The price does seem high to me also. Plus the rough idle at stop is a sign of fuel pressure issues, or other related problems. I've been diagnosing my 2001 Sportage for a month now, and still have the rough idle. I've failed smog twice, and am now narrowing down a too lean condition, which is related to either poor fuel pressure, or low operating temperature, or both.

Update:
I found a second smaller vacuum port in the middle of the intake manifold under a slightly larger hose. It was open so I plugged it, and put a new thermostat in. Vehicle idles rough until completely warmed up.