Haven't had time to do any troubleshooting yet. I'm hoping you guys can save me some time by pointing me in the right direction.

Here are the symptoms -
When I try to start the truck after it has been sitting overnight, it behaves as though the battery has been drained, although the dash lights and stereo/amplifier still work. The starter starts to turn, then stops as if it can't get enough current. I use my booster pack & it fires right up.
Some type of parasitic drain right? ...but something else happened a couple times that is confusing me.

It did the same thing after work, but instead of jumping it, I drifted it forward, thinking I might drift start it.
I didn't have enough speed, but pop the clutch anyway and the truck stops. Then I try the key again and it fires right up. I've done this twice now.

Not sure if it's relevant, but I replaced the starter contacts a few years ago and the alternator in december. The battery is pretty old and everything else is stock w/220k miles on it.

Anyone have any insights about what is going on?

Thanks