New battery. New alternator. New starter. No power!!!

[CoffeeBee]

have a 1998 4.3L RWD astro van i just purchased. I put a new battery. New alternator. And a new starter on it. My fuses are good. (i didnt replace relays). And i have done a full tune up. (spark plugs. wires. Distributor cap and rotor button). I have not done the engine control module or ignition control module but might need to. I also have a problem with my headlights. Buzzing in fuse box when i turn on brights while lights are off. And when lights are on. The brights dim my light instead of getting brighter. Im replacing relays next. But For some reason i have a power drain. Only when the key is on. I can jump the van and she starts right up. But my voltage drops until it stalls in less than 5 minutes. Any suggestions on what could be draining the power? Ive had her a week and already put over 1000 in repairs. I also checked grounds for alternator and motor grounds. What else could it be????

[M_a_t_t]

Have you used an Ammeter between the battery and cable? Start pulling fuses until the amps drop. When it drops there is a problem with the circuit of the fuse you just pulled.

[markmitch]

Also check all your ground wires for breakage clean the grounds on the battery cables too. I had a situation where every time I turned the parking lights on it blew a fuse and it turned out to be two things not sure which one caused the problem cause i fixed them both before trying again but one hot wire from an old set of lights was pinched into the body and a ground for the tail lights was broken. After i fixed them both-problem was solved. Auto electrical can be a pain in the butt. Keep us posted with your progress please. Mark.

[CoffeeBee]

I have taken it to a shop for the inspection. I hope they can diagnose the problem. I found out this morning before i took it into the shop that i also have a battery light out. In having them do a full electrical inspection and suspension inspection