as soon as the thing started to move, it lost power and the head lights cut out

[95tsiawd6blt]

hey on my 91 gvr4 i have had a very weird problem with the car. The car is currently not running due to other problems, but i know once its fixed its going to do the same thing it used to. I had a problem where when i would floor it, it would start to spool, and as soon as the thing started to move, it lost power and the head lights cut out. As soon as i let off the throttle, the headlights came back on like everything was fine.
I did not find anything grounding out anywhere. I took my alternator off, had it tested, and it came back good. please help me if you know what the problem is.

Thanks

 

[luv2rallye]

Check if battery is tied down so it won't short against metal.

 

[turborebel]

If your battery is secure, use a volt meter in the car to see if there is a drop in voltage when this happens.