engine "surging" and tach jumping on 2002 Chevrolet Malibu

The car has 92,500 and in the past year I have noticed that when I am accelerating in 4th gear (especially at higher speeds) the car feels as if it is thrusting or surging and the tach jumps a small amount each time. I usually need to downshift to 3rd in order to stop it and be able to accelerate. Oh and the check engine light is on about 95% of the time. I have a feeling that this will sooner or later become a big expensive issue... Can anyone out there give me their thoughts on what might be going wrong?

Asked by for the 2002 Chevrolet Malibu
Autoknowhow is absolutely right, the check engine light being on indicates a fault code is stored in the on board computer in your car. This code will lead to properly diagnosing the problem with your car but a scan tool is required to retrieve the trouble code.
1 more answer
STOP WHAT YOU ARE DOING!!!!!!! There has to be a trouble code stored in the computer. Retrieve that and then ask for HELP.