I have a 99 silverado with a 5.7 liter vortec and for some reason it runs like s... sometimes. It seems that when this happens i pop the hood and shake all the wires and it will run fine again. I've also notice that it only does it when the weather is crapy! Any ideas as to what the problem is???

Sounds like bad plug wires

You might want to change your distributor cap wile your doing the wires.

And rotor. Which wires do you shake... sparkplug wires, battery cables, alternator wires, etc...?