My '04 Crew Cab (V6 3.3l, auto, 55K miles) is intermittently doing the following: the speedo dies, at some point the engine starts lurching as if I was tapping the gas pedal. It will continue until I shove the shifter into neutral briefly then back into drive. After that it may return to normal or continue to repeat every few minutes. It will go for days and not do it. The speedo doesn't come back up when I put the trans into N, but will when it wants to. If the lurching happens while the cruise is on it kicks out and the SET light blinks until I turn the engine off. The Service Engine light is on and the codes are P038 knock sensor high and P0500 speed sensor circuit fault. I have cleaned four ground contacts and the battery posts. Could it possibly be a faulty speed sensor? Thanks.