I have a 2000 Toyota Pre-Runner x-tra cab V-6 , Has been trouble free from day one. Has 55,000 miles now and has been serviced every 5,000 miles with Mobil 1 oil and factory filters, I do my own service. Over the last few thousand miles I have noticed a Slight engine knock at idle. usually only hear it when you are in the garage and it is quiet. You can also hear a slight knock at low speed , Anybody else hear this in their trucks? Any ideas? Scott