Pontiac Repair: 97 Gran Prix 3800 stalling, throttle position sensor, ac delco

Question
My daughters 97 Gran Prix 3800 has begun stalling when coming to a stop or turn and also when backing up.  The local shop diagnosed the problem as a throttle position sensor and replaced it.  The issue still remains.  He is now getting a read out of "throttle/pedal/position sensor/switch a circuit range/performance.  Short of replacing the TPS again what are other ideas you may have?  They checked all the vacuum connections and all are tight.  He also got a readout of "Barometric or Varometric Pressure" sp? He is not familiar with this.
Thanks

Answer
Hi Lynn:

well low spped stalling on these is strange. I would start by # 1 using a TP sensor that is an AC delco part no aftermarket electronic parts should be used at all. that being said with a good tp sensor the volatge reading needs to be checked at idle and make sure it's the proper setting the aftermarket fits all ones some are adjustable and if it's not set right guess what same problem... I would look at a dirty throttle plate and throttle bore and or a dirty idle control valve. These engines were also noted for bad MAF sensors but usually they cause an erratic idel hesitataion and or a stall at any speed not just low speeds.. that is where I would start looking. good luck :)