Racing idle rpm

[clanky]

I'm new to the VRCC but have read numerous very helpful posts. I need some guidance.  I have a 98 standard with 115K on it.  I have not had to do anything to this wonderful bike in the 16 years I've owned it except changing tires, oil, coolant, one air filter and gas. I've always used Stabil fuel treatment prior to winter although I have been able to take a ride at least once a month every month since I bought the bike.
My first ride this year was uneventful, the bike started right up and I went for a 20 minute ride. I recently installed the MC Cruise system and was in the process of verifying the installation when the instructions asked to start the engine.  I have verified that I installed the throttle cables correctly and they are well lubricated and the throttle indeed snaps back to the idle set screw. All 6 carb throttle plates move in unison.
When I started up the engine it immediately races up to 4000 rpm. Upon gradually opening up the throttle the rpm goes down and the engine is struggling. After a couple of seconds the engine then ocillates between 4000 and 1000 rpm.
I pulled the air filter box out so I could see if there were any hoses off. I did find the vacuum line to be a bit brittle so I replaced them. Still have 4000 rpm idle. I noticed that the "butterfly" plate that is vacuum actuated is pulsing at the frequency of the engine rpm and the "butterfly" is moving up and down about 1/4 so fast that it's a blur.
Again this is the first time in 16 years that I have ever had any Valkyrie trouble. Was I running on borrowed time? Any suggestions would be much appreciated.  Thanks Clanky

[Firefighter]

Others might know for sure but to me it sounds like an intake leak or vacuum hose leak. I assume the new cruise control is not opening the throttle? If this started with the install then I would retrace everything that I did. Did you install a vacuum canister for the cruise control?  Will have to go over everything. Let us know.

[clanky]

There is a vacuum servo unit. I disconnected the vacuum supply to it along with disconnecting the multi-pin connector to the cruise control computer. Right now cruise control is NOT in the loop other than the "CIU" (Cable Interface Unit) which allows either the servo or the handle throttle to activate the carburetor throttle plates. Again I checked this set up very carefully and took my good time getting all the cables lubricated along with the grip lubricated and in all handle bar positions the throttle snaps back onto the idle screw.  In fact I've the idle screw so low that the throttle arm doesn't touch it, ie the throttle plates are fully closed. 

[Ricky-D]

Since the throttle is oscillating as you observe, the only answer can be the new cruise control you installed is the culprit.

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[clanky]

The cruise control components have been disconnected ie main computer disconnected, vacuum supply to servo disconnected, tach signal disconnected. The only thing still connected is the CIU (cable interface unit) which allows either the hand throttle or the vacuum servo to pull on the main throttle cable. Since the servo has been disconnected from vacuum it cannot act on the throttle.

[Gryphon Rider]

Call MC Cruise.  I hear their customer tech support is very good.