woody wood pecker?

Hi! I have a 1998 Mitsubishi Galant and I am getting a fast knocking sound, sort of a woodpecker sound when I accelerate between 65 and 80 mi per hour. it seems to come from the front passenger part of the car and I feel the vibration in my gas pedal too! To add, I have always had a "noisier than usual" front passenger suspension on rough roads and the only thing the dealer told me was that my car had a recall for the lower ball joint but they claimed they fixed that (though it never went away). Can anybody help? I tried at least 3 mechanics and their diagnosis range from a wheel baearing to the transmission. They all say different stuff so I am confused! I am going nuts! Anybody expert on Mitsubishi?