I have been hit with a rash of P0068 MAF/Throttle Body correlation codes that have put the car in Limp Mode on track at both Charlotte and Daytona. Symptom typically comes after letting off and downshifting from top speed off of the banking at both tracks. Oddly did not happen at either VIR or Lime Rock. Shop manual suggests, air leak at PCV system, vacuum leak, bad MAF or bad Throttle body position sensor. If anyone has had this problem and solved it I would appreciate the input.