PLEASE HELP! I have a 2003 ford taurus ses. About a year ago it started running 3-4000 rpms when i put it in park. When I'm accelerating around 35-45 mph, theres a loud rattling under the hood and when I let off the gas the car briefly surges. Now it accelerates by itself and still wants to go when I'm at a stop. I've had spark plugs and wires replaced, gasket heads, pcv valve, MAF sensor, iac valve, egr valve, throttle position sensor all replaced. Throttle body and intake totally cleaned. Mechanic did a smoke test and found no vacuum leaks. Also had throttle cable checked, perfectly intact. No one can figure this out. Please help. Also sometimes if I adjust the pedals while going down the road the rpms increase.