Originally Posted by David M

About half the time my engine has full horsepower, which is to say that it is producing its full 330 horsepower.

The other half of the time the engine is producing perhaps 30% to 40% of that horsepower. When it changes it is pretty much random. It can and does happen on the highway driving at normal speeds.

I have no idea what is causing this.

Could it be an Engine Control Module problem? A fuel pressure problem? Could the mass airflow sensor not be working? Could it be a vacuum leak?

My car is a 2005 convertible SRT6.

Thanks