Cruise Control problems of the 2000 Volkswagen Passat

Vehicle accelerated on its own while I was driving on the freeway. The freeway was congested and I had just accelerated quickly to move into the left lane to avoid a semi truck entering the freeway on my right. I took my foot off the accelerator but the car continued to accelerate. I immediately pushed hard on the brake to avoid hitting the car in front of me. I had to apply considerable pressure to keep the car from increasing speed. I then placed the car in neutral and took my foot off the brake. The tachometer showed the engine revving up over the red line to 7000 rpms. Fearing that the engine might be damaged I put the car back into gear and controlled the car by applying the brake as hard as I could. The acceleration slowed after about another 30 seconds or so to the point where the car was traveling at a sustained 70 mph without my foot on the accelerator or brake. This continued for several miles and eventually the accelerator began operating normally. During the last portion of sustaining 70 mph I tried switching cruise control on and off several times but this had no effect. After I got off the freeway and stopped, I checked the floor mat or anything else that might have interfered with the accelerator pedal and did not observe anything out of the ordinary.

I have a 2000 Volkswagen Passat GLS 5 speed manual car with 65000 miles; for past 6 months while cruising on the highway with speeds above 65 mph, the cruise control automatically gets engaged many a times even though I have never switched the cruise control on. This has happened atleast 10 times in the last 6 months and I have no way of knowing how and when it gets engaged. I have to be always alert to press the brake to disengage-engage this. Please let me know if you need more information.

When driving with cruise control set at 55 mph, upon moving down a slope of a hill, the engine raced off and vehicle, a 2000 vw Passat accelerated uncontrollably.