mog ruith,
i had the exact same problem and i never did track it down, although i checked some very reasonable and common sense tips that seemed like they ought to cure the problems [like worn/defective bearings, binding, camber, toe-in, oddly worn tires, binding hinge-pins, bad servo, stripped splines, loose bell & crank, faulty rx/tx, battery, etc, etc.]
the car runs like a peach, but in the beginning it pulls left, then straightens out, then eventually pulls right, and then tapers off to straight again about the end of the battery pack. i've gotten really good at on the move trimming.
if u ever find the cause, i'm dying to hear it.
