Hello, my 1999 Grand Prix GT (177k miles) is having some issues and was wondering if anyone had any suggestions on what could be wrong. The car sometimes randomly stalls when driving (usually when going above 50 mph or if you try to accelerate very quickly) and doesn't start back up for around 5-10 minutes; this has happened to me around 4 times in the past 3 weeks. When this happens the electronics keep running and you almost don't notice it has turned off until you see the tachometer at zero and the steering stiffen up. Other times when driving down the road the tachometer would suddenly dip to zero rpm and the traction off light comes on (pressing the trac button doesn't turn it back on); all this happens without a single sputter and the car continues to run fine for the rest of the drive. Turning the car off and back on after this happens usually gets the tachometer to work again. Sometimes it also refuses to start for a while after having it parked for an hour or so after turning it off. The car runs very smoothly otherwise without a lot of vibration and usually starts up with the first crank.
I have read a lot of threads and I have seen that people with similar problems had a failing CPS, but my check engine hasn't come on and I even took it to Autozone and they hooked it up to a scan tool and found no codes. So far I have put in a new starter, battery and radiator (which was leaking coolant) but the problem still persists. I am hesitant to take it to a mechanic because i doubt that they would be able to reproduce the problem in the shop as it usually happens after driving it.
Hopefully you guys can help me out with this problem because I have to drive the car for 2000 miles in a few weeks and don't want to end up on the side of the interstate.
