How do I reset the reduced performance/safety mode on my 2006 v8 gto?

I suggest you take your vehicle in to have a computer diagnostic ran on it. They'll probably have to reset it with their equipment.

this is the limp mode and is used when there are serious problems with the engine and gear box . IT is instigated by the ecm to protect the units. have the fault codes read to determine where the fault is . Check oil and coolant levels and engine temperature

reduced power , electronic throttle control problem . Reduced Engine Power Mode
When the ECM detects a condition with the TAC system, the ECM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions:
• Acceleration limiting--The ECM will continue to use the accelerator pedal for throttle control; however, the vehicle acceleration is limited.
• Limited throttle mode--The ECM will continue to use the accelerator pedal for throttle control; however, the maximum throttle opening is limited.
• Throttle default mode--The ECM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
• Forced idle mode--The ECM will perform the following actions:
- Limit engine speed to idle by positioning the throttle position, or by controlling the fuel and spark if the throttle is turned off.
- Ignore the accelerator pedal input.
• Engine shutdown mode--The ECM will disable fuel and de-energize the throttle actuator.

On this website you find fuse box diagram and description for Pontiac GTO (2004)


Pontiac GTO 2004 2006 fuse box diagram Auto Genius

when you have the fault codes read to find the exact sensor failure or cause , have it fixed then reset the ecm as the ecm will reduce the performance(limp mode) for safety reasons

Headlight adjustment requires specialized tools.

Hello and welcome. here is the oil drain plug torque spec for your vehicle

Oil Pan Drain Plug
25 N·m
18 lb ft

This would be a defective part in the steering column and I would think that this should be a safety recall issue.  Do a google search on the recalls on your vehicle to see if this would be covered for free by the dealer.
If not - find a reasonable and trust-worthy mechanic as dealer rates can go from $70. to 100.00 per hour.
Try wiggling the wheel as you turn the lock and jiggle the shifter.
I would replace this unit as it is potential for a crash!

You will need what is called an oil vacuum pump. They are not very expensive (around $20-$30 US) & are usually available at your local auto parts outlet. They are basically an oversized syringe with a flexible rubber or plastic tube instead of a solid steel probe & will usually hold about a metric litre. Hand operated. Use this to withdraw as much oil as you can from the Diff, it is impossible to get every drop. You will also find it handy to refill the diff, but flush it out first with kero or diesel. I also recommend draining all you can in one step, then waiting 1/2 an hour to 45mins and doing it again to get the last bit.

the onboard cpu engine control module is going into closed loop. you need to take it to a different shop and see if they can hook up a diagnostic computer and find out why it is doing it. closed loop is there only to get you off of the hiway if you are having problems not to keep driving with it like that. What ever is causing the closed loop condition could cause serious damage if not fixed.