I just purchased a 95 F150 XLT. It has 300 6 cyl. and 40,000 miles. When I start it (cold or warm weather) the RPM jumps to about 2000 then back and forth to about 1000 until it has warmed up, then idles at about 600. Is this normal, or a vacumme leak? How do I find the leak if any? Don't hear any unusual hissing under hood. Also the driver's side door speaker sounds like it has distortion in it. While driving sometimes all the speakers will go out when I hit a bump. My radio still has power and the equilizer display is still on so I know it's getting a signal. When I hit the door panel with my knee it comes back on. What causes this? Sounds like I can hear something arking in either the speaker or power windows and locks buttons. How do I remove the door panel? What size speaker is in the door? I assume they are still factory since an old man owned this truck and never cared much about the radio. Thanks for any info!