I have a 2001 truck which has 24,000 miles on it. I do no t use it every day and in fact there are times when it is not driven for 3 or 4 weeks. Yesterday I started the engine and discovered that I had no power assist it the steering and in my brakes. I shut the engine off, went and looked at my manuals and came out to check the vacuum pump. Started the engine- still no steering- vacuum ok. As I was pulling the truck into the garage, everything started to work fine. I have no leaks, fluid is clear and resevoir was full. My thought is that a valve stuck open, because of sitting so long? I tow a 10,000 lb trailer and do not want to have this happen on the road. Any thoughts are appreciated. Tom 
