I got this from Mitch on the VMC and it worked great for me.

For those of you that are having problems with erratic cruise contol operation. Try this Cruise Control Cable Lash Learn Procedure:

1. Press and hold the resume and on/off buttons on the cruise control switch.
2. Turn the ignition key to on.
3. While holding both buttons, start the engine.
4. After the engine starts, watch the cruise indicator lamp on the indicator display
until it goes out.
5. When the cruise control lamp goes out, release both buttons at the same time.
6. Press and hold the resume button. The cruise control indicator lamp should
illuminate.
7. Listen for a brief increase in engine RPM (very slight RPM increase) as the cruise
control module performs the procedure. The cruise control lamp will go off during
this procedure.
8. Release the resume button when the engine RPM drops down to idle speed and
turn engine off.
This procedure is used when replacing the cruise control cable, but try it. Maybe it will help. This info is right out of the service manual and it states that failure to perform this procedure will result in erratic cruise control operation. This procedure takes any slack or free play out of the cruise cable where it connects to the throttle body.