Trailblazer 2008, just got a new thermostat, throttle body, exhaust manifold, and cam solenoid. Driving the truck everything's fine and then everything just drains. Heat lessens, lights dim, it's like you went from 100% power to 30%. When you try to start it, it turns over, but won't start.
I don't know what to do and I have to drive 50+ miles tomorrow and this has already happened twice in one night. It seems the truck can't idle. This seems to happen when I'm at a stop. If I keep the key turned and grind it, the truck starts, also if I stay on the throttle and in neatural the truck stays running.

 

Battery, alternator or battery cable problems. Check the battery cables first for looseness or corrosion.

 

I agree, check all your grounds for cleanliness and tightness.