1995 Grand Caravan, 3.3L

My girlfriend was driving today and she said it started to make a loud shuddering noise without any shuddering occurring. It seemed to happen only when she stepped on the gas.

I started it up when I got home and it sounded okay. I did the check engine code key method, and got 12, 34, 55.

12 is fine, disconnected battery,
55 is fine

34 is "cruise control servo failure"
What do I need to be concerned with for this? Is it terrible, or does it just mean I can't use cruise control? And would this cause the noise she was hearing?