i bought a new battery and belt and alternator. but even when the key is on auxillary and the car is shaken the power seems to fade and when the car is started it doesnt seem to produce as much power as normal. im at witss end i checked the connections but cant find the problem. what else could it be?

 

Connections.

What kind of charging voltage are you reading at the alternator output stud? How does that compare to the voltmeter on the dash?

 

If shaking the car changes the available power, start looking for loose connections.
Maybe a missing or loose ground between the block and frame.