Hey guys I posted something similar before but I am still having issues. I have a brand new battery, a year old alternator, and a freshly rebuilt starter. All connections are tight and wires look fine. My T4R is a 97 with 150k and is awesome in all other aspects except if I let it sit for about 48 hours without being driven or started it will loose its charge almost completely to the point of not starting. If I drive it everyday it seems fine. This sucks because I use it as my weekend driver. I live in FL and the weather is not a factor (80-90 everyday). I do have an aftermarket stereo and I make sure to turn it off before I turn the ignition off just in case. No help. I have never seen a truck do this. Any suggestions?

Have you had the new battery tested? I've seen new batteries that were no good.

as far a troubleshooting goes I would try this:

you need to determine if the problem is a voltage drain or a failure to charge the battery.

so charge the battery using a 120v plugin charger. Then at 6pm hook the battery back up to the car. if the car starts fine in the morning, that is a good sign but repeat the next night just to be sure. Batteries can be unpredictable.

if the battery only holds a charge using the above method vs normal driving to charge the battery, then perhaps your alternator is not able to charge the battery properly.

(sent from droid x)

Suggestion above is good. You could also just try leaving the negative cable off for 48 hours and see if it starts strong when you reconnect. If it does, then you know you have a parasitic drain, which is also a good search term for finding out how to track it down.

When you reconnect the battery, listen closely for any relays clicking. I had a set of Hella fogs where the included relay plug was mis-wired and the relay coil stayed energized 24/7. It would run the battery down in almost exactly 48 hours. It was the clicking when I connected the battery that eventually gave it away when I started parasite hunting. As far as I know, no relays should energize just from connecting the battery. That wouldn't make any sense.

Great advice guys. Im going to try that this weekend. I will keep you all posted.

My Amplifiers were to blame guys! For some reason the 2 amps were drawing power while off.... Not sure why. 1 $5 cutoff switch and problem solved. Thanks for all the input.