1999 Mitsubishi Galant. Idle went from surging last week to sputtering this week.
Last week, my 1999 Mitsubishi Galant (which has been very reliable until now) engine idle surged & tried to leap across intersection when I applied brakes at stoplight. Now, after a week in which I noticed nothing really unusual, the idle is sputtering and very intermittent - actually caused the car to die at stoplight. I have to apply a little gas to get the RPI up to 1 so it won't die at stoplight. Budget is very tight and can't waste money. What is the most likely cause and cheapest/best fix to try first? If that doesn't work, what are next steps. Can it be analyzed with a computer at the dealer?