99 Suburban wont start- Electrical Issue

I have a 99 Suburban 2500 v8 7.4L that has a new battery, alternator, and a fairly new starter but won't start. Symtpoms:

I put the key in the ignition and roll the key forward the dash lights don't come on and the battery guauge reads zero. The engine fan spins and it wont turn over.

There is power because the windows, heater, radio all work.

Intermittently, I get the juice and the dash light indicators all light up with the battery showing 14 amps and then the truck starts right up.

So what part or connection is faulty to cause no power?

Help! Thanks in advance.

My first suspicion would be the ignition switch and/or the wiring to it.