2002 Ford F-150 • 84,000 miles

It started by a minor sputtering while my gf was driving it. It became seriouly worse to where while drving at a steady speed it would jerk badly but if I drove and shifted at a high rate of speed if was fine until I released the gas pedal and symptoms returned. I let it set for a week then drove it and it was fine until I shut the engine down and restarted and the symptoms returned. This scenario has happened twice. Autozone tester reported a bad cam sensor. I replaced it and it did not work. I foolishly asked an online (32$ expert) mechanic who said it was a crank sensor. I changed that too plus put a new fuel filter on it. Before all this began my truck had been performing perfectly it only has 84k miles but my gf said that she had heard a sound like a pulley was squeaking but I never heard a sound.
January 28, 2013.

Check out the related content below while we wait for the question to be answered by a professional mechanic.