Mitsubishi Repair: rpm jumping, mitsubishi eclipse, dsms

Question
1991, Mitsubishi Eclipse 2.0 AWD Manual.

I just bought the car yesterday, with only 62,000 miles on it.  I'm not a mechanic, but my brother is, he doesn't have that much experience with DSMs though.  The first second we started the car it started idleing irregularly, the rpm was constantly going up and down.  It actually goes from regular idling rpm down for a second and then back to regular again.  It doesn't really make any power now.  The guy said it could be the air sensor or something.

What do you think are the possibilities?

Answer
Rob,
You have a common occurance that can happen on older DSMs (including just about any car) called "idle surge".  Idle surge can be caused by a dirty throttle body, malfunctioning EGR valve, or a malfunctioning Idle Speed Controller (ISC).  If you have a service manual for your car (both Haynes and Chiltons make one for your car), they will tell you how to test for those malfunctioning items and how to remove and clean your throttle body.

You should reference this site: http://vfaq.com/index-main.html
That site will give you all sorts of information about your car, including a deeper explanation about idle surge.  Just look under the 'Intake' section.
Good luck!