Good Chance this is caused by a faulty O2 Sensor. I had the engine light stuck on in my 2002 Montana and replaced rear O2 sensor and it turned it off.
"http://wiki.answers.com/Q/What_causes_your_2006_pontiac_grand_prix_driver_info_center_to_display_reduced_engine_power"
It needs to be Re-Set.. Most places can do it for no cost. takes less than 10 seconds.
What causes a 1998 Pontiac transport to run hot and engine shuts off
The most likely problem is a Head Gasket. Sorry Man.
Low Coolant. Poor coolant circulation. Intake gasket. Head gasket.
You are OVERHEATING. You most likely have an intake or Head gasket problem.
What causes a 1997 Pontiac sunfire gt with a 2.4 liter engine to stall when stopped at a light
put on a new PCV valve.
One of the possible causes of a Pontiac Bonneville to jerk during acceleration is that the car needs a tune up. The engine misfiring can lead it to jerk as you accelerate.
Could be low coolant, stuck thermostat, bad heater control head (if climate control)
Reduction in power density. Power density is the power produced by the engine per volume unit. Reduced volumetric efficiency means that less air/fuel will be delivered to the engine for a specific engine volume.