Originally Posted by ala_xfire

Josh is saying :
1. Replace the MAF sensor. ( Mass Air Flow sensor )
If that does not resolve the issue, then
2. replace the CPS ( Crankshaft Position Sensor )
If that does not resolve the issue, then
3. replace the Camshaft Position Sensor.
If that does not resolve the issue, then
4. Use some method that detects vacuum leaks to ensure none exists.
One method is to use an UNLIT propane torch and pass it close to any suspected source of leak, if the engine smooths out, you found the leak.
BE VERY CAREFUL WITH THIS, AS YOU ARE INTRODUCING AN EXPLOSIVE ELEMENT INTO AN AREA WHERE SPARKS MIGHT EXIST !!!!!!!!

I disclaim any responsibility if you or the mechanic chooses to use this method.