Anti-theft Controller problems of the 2005 GMC Envoy

Dt: consumer owns a '05 GMC Envoy and has difficulty towing a trailer within gm rates, gm states that his Envoy can tow a weight of 5,800 pound capacity, however he feels the vehicle is unable to maneuver a travel trailer of 3,400 pound capacity. The consumer has been to the dealership twice for this. The dealer stated there was nothing they could do. Consumer has pulled the trailer with other vehicles and it pulls fine but when attached to the Envoy there is a problem. Consumer feels it is not with the suspension of the vehicle but within the engine which is a v6. When pulling trailer for a distance as little as 2 miles the engine heats up, and he experiences a loss of speed and engine the bogs down to 30 mph. Envoy is equipped with the 373 axle ratio and can not pull an enclosed 24ft travel trailer on it's 6 cylinder engine. The 2nd trip to dealer, the service manager did duplicate this problem and suggested the consumer needed a v8 engine. Also, there is a electrical problem that only occurs when the engine is running. Consumer gave examples of automatic door locks unlocking by themselves and the anti theft system enabling itself resulting in a shutdown of the vehicle. Took to dealer 10 times for this problem. Dealer could not duplicate problems. The dealer said gm would not authorize repair unless they could duplicate problem. Has contacted gm customer service at least 100 times for these issues without any luck. No repairs or corrections as a result. Consumer is still experiencing these problems as a result.