2003 Monte Carlo SS, 241,102 miles

The surge issue started about two weeks ago between 55-60 mph under partial throttle only. Since it had been a tick over 75,000 miles since the last ATF change, I decided to change the ATF and filter (Valvoline Max Life and a Power Torque filter) reasoning that the surge was occurring about the time OD kicks in and there may be a partially clogged filter.
Fluid and filter that came out was not unusual in any way (e.g. strong discoloration of fluid, metal or plastic shavings, etc..). The surge is continuing still.
Today, while enroute to work, I had my cruise control set at 70 mph and for no good reason it turned off. I never hit the brakes, touched the cruise settings, etc... I then noticed that the LED in the "Set" button was not illuminated. Several attempts were made to turn it on but the light stayed out.
All of the fuses that control the CC are in good shape and I found no obvious signs of a disconnect under the hood.
Back to the surge: I plan on spraying carburetor cleaner along all of the vacuum lines and fittings in the hopes I'll find a leak which in turn could cause the surge problem.
That's it in a nutshell MCF friends. Any suggestions?
I also just changed all six plugs and wires, conducted voltage and Ohm tests in all ignition areas as well as replaced the catalytic convertor due to it being bad,
Lastly, all filters have recently been replaced with Wix brand which is my brand of choice.

 

Dale:
Just for the sake of checking..
I would consider checking fuel pressure at the fuel rail...
Could also possibly have a fuel filter that needs to be changed...(If you haven't already).

Whens the last time you changed the air filter?
Could be also something as simple as cleaning the MAF. (Mass Air Flow Sensor) Could be the combination of both...

Or like you had summized...a possible vacuum leak.

I'm sure others will chime in with further possibilitys..
Keep us posted on your progress and what the final resolve was..

 

The air and fuel filters have recently been changed in the last few months with my brand of choice: Wix.
For the sake of argument, I did check for any obstructions in the air-box inlet and the condition of the air filter itself which was OK.
As of today, I lost all radio control via the steering wheel.
With that said, I'm leaning away from the upper-most detent control that disengages the CC under braking and thinking it may be the clock spring due to the radio and CC both being wired through this single component.
I performed a simple lock-to-lock on the steering wheel and a full left-lock will cause the "Service Traction Control" light to pop. After bringing the wheel back to dead center and turning off the ignition then restarting the car, the light clears.
The traction control and ABS are both working at 100%.
Thoughts on the Clock Spring?