Honda Civic Cruise Control engages fine, but the engine speed keeps increasing even after turning it

I have a 1999 Honda Civic, 5 speeds, with about 72,000 miles on it.
The car drives great.
The issue has to do when I use the Cruise Control, It engages fine,
but the engine speed keeps increasing even after the dash cruise
control light goes off and I let off the gas, step on the break and/or
turn the main cruise control switch off. Stepping on the break will
not slow the car down. If you put the car in neutral, the engine just
whines and keeps up its high rev.
I purchased the car from a brother-in-law at 43,000 miles. He claims
that he never used the cruise control. The 1st time I tried to use the
cruise control after I purchased the car was a very scary experience.
The engine speed kept increasing even after stepping on the break and
turning the cruise control main switch off, the only way to stop the
car was to put it in neutral and turn the engine off via the key
switch. I was left in the middle of the road wondering what has
happened.
For safety reasons I disconnected the cruise control until now.
I want the car to be driven by other members of my family (my kids)
without the possibility of any one getting hurt. Also, I would like to
be able to use the cruise control while driving long distances, for
this reason I made up my mind to fix this problem.
I got the Honda Civic factory manual and checked the entire cruise
control system.
Everything checked OK, switches, etc. Since I have another Honda Civic
of the same model, I replaced the cruise control unit, the Cruise
control actuator, The Vehicle Speed Sensor (VSS) the vacuum tank, The
Vacuum hoses and the Check Valve, the same result.
I raised the front of the car and verified that the actuator cable
moves freely when the cruise control is set and it does.


Questions:
Is this a known issue?
What is the cause of the problem?
How to fix it?

Thanks