Intermittently issue of the car shaking back forth while driving and the check engine light turns on?

Hi,

My car rapidly shakes back and forth, (ie, judders/jerks), every now and then, when driving on the highway. The Check Engine Light also comes on.

The mechanic said that to fix this problem, he performed the following:

1. Changed all the spark plugs.
2. Total tune-up.
3. Fuel System Cleaning.
4. Changed 2 front struts.
5. Changed the fuel pump.
6. Changed the fuel sensor.
7. Changed the MS flow sensor.
8. Changed the oxygen sensor.

But the problem still exists!

Now, he is telling me to change the Catalytic Converter System.

What might be the problem? Any ideas on what I should get fixed? Any help is appreciated!

Thank you!