RPM's raise and drop then car dies. Any ideas?

[ChasePontiac]

Hello, all,

I've googled far and wide and can't find a solution. No codes are showing.

History: 04 Grand Prix (206k). While driving down the highway, RPMs will drop off and/or jump up suddenly. When this begins, the throttle will be hit and miss and 20-30 seconds later the car dies and I have to pull over and start again. This has happened 3 times and each time it started back up on the third try.

Prior to the problem and within the last month, I replaced the air filter, thermostat and MAP sensor for emissions testing. After the first time it died, I cleaned the TB and the MAF sensor as I'm familiar with that process since I had the problem of starting the car a few years back. However, it's happened again twice since cleaning.

After reading everything I've found online I've seen suggestions such as Crank Position Sensor, Throttle Position Sensor, Wire Harness, Ground Wire Corrosion, Loose Belt Tensioner, IAC, etc.

Can anyone help? The most recent post I've seen is 2011 so hopefully someone has a solution by now. ....Hopefully?

Thanks.

 

[Scottydoggs]

sounds like a bad crank sensor. if you see the tach ever drop to zero while driving, then it dies after wards. crank sensor for sure.

 

[ChasePontiac]

Thanks, Scotty.

I have a new one arriving tomorrow actually. I don't believe the RPM's have dropped to zero but I can't say for sure. The issue begins when the car has been running around 2000 for while then will either fall to ~800 or jump to 3000 randomly. Then it seems to sputter a bit before it dies.

Hopefully the CPS will resolve the issue. I just saw so many suggestions online I figured I'd post for myself.