2005 1500 LS 5.3 Vortec Gas - has new alternator and battery. 2 issues randomly will lose acceleration (throttle)power while driving, usually can see battery gauge flutter right before. Throws code U0701, you can unplug the connection to the throttle body, clear code and it will run like normal. 2nd issue battery drains when sits over night even after being driven, but not every night

 

It's hard to get to but, on the back of the head on the passenger side, there is a ground wire (black with a white stripe). Take that loose and clean the connector and the head. It's a main ground that controls the throttle body and other components.

 

As mentioned, the driver's side cylinder head to the firewall is a necessary ground. But, a key ground connector for the ECM, that causes many issues with faults is behind the front bumper on the driver's side. Use a flashlight to look through the bumper cut-out to the left of the parking light, as you face it. You should see one or two black wire eyelets under a single bolt. Remove that bolt and clean the area with a wire brush, and also clean the eyelet contact surfaces (sand paper also works). Re-install and paint/seal over the connection to prevent moisture penetration. Since you only need .5 volts for the throttle position sensor to the ECM, this ground can help solve many issues, including random system codes. I hope this helps.