Mitsubishi Montero 2003 active skid control system indicator lights turned on and the car is now sputtering?

Mitsubishi Montero 2003 active skid control system indicator lights turned on and the car is now sputtering as if to turn off. What could this be? I took to a couple mechanics. One says it is the catalytic converter and O2 sensors and also plus nad wires. The other says speed sensor. What are your thoughts? Please help.