92 Blazer cranks no crank then cranks
 

My Blazer seems to have a mind of its own. This morning cranked right up. Lunch time turned over really slow like a dead battery. Battery is fine. After lunch turned key nothing turned key again starter clicked, turned and held for 3 seconds cranked right up. Does this sound like an ignition switch?
Any one have the same problem?
Thanks

Update
 

Now the truck is dead tried to start it this afternoon no click everything went dead inside truck had batt checked out its good it's only a year old. I will change out the ign switch tomorrow. This is the only thing I can think of. Due to shuts all power off.

Make sure that the power cable to the starter is not grounding out anywhere.

Check the connections at the battery and starter, make sure they are VERY clean.

Take them off, clean them very well.