FWIW I think $60 for a firm diagnosis is money well spent. I've had intermittant limp home/ASR light problems, mostly in the winter when I've got my snows on, and I think it might be related to a tire size discrepency since it hasn't happened when my "summer" tires are on.
Most recently, however, I had a limp home/ASR light/ABS light condition. My independent tech pulled codes and found it to be a bad brake lamp switch, of all things. If you look at the schematic, the engine computer receives a WIDE variety of inputs, any one of which can throw it off and produce the dreaded limp home/ASR condition, so it MAY not be the TBA (yet -- ).