Well, I'm back to square 1....A brief history from my last post.
When I put in the key and turn it to start, half the time it wouldn't start, either a click as in a dead batt. or a bit of a "whine" all power was dead, even lost radio settings, which is wired to one of the acc fuses {don't know which}
Anyway after checking ALL the connections associated with starting I tracked it down to the switch {I thought} I would jiggle it the key and or bang on the column and all power would come back and I could start it.
Ok...I replaced the electrical part of the switch on the column...it started cranking fine with no problems, even turned easier. Today it did it again...went to start it and it just clicked......so I left the key in the on position, turned on the headlights which were hardly on, went under the hood and messed with wires around the batt. the reg. and the few "taps" to see if I could jiggle something.....nothing...BUT I did hear what sounded like a faint sizzle from the batt. post....I go jiggle the key and lights and radio came back on full and no sizzle from the batt.
SO it HAS to be SOMETHING switch related.
What do you guys thing?????

 

Sounds like to me you need to change some wires out, also possibly the battery. When mine did almost the exact same thing I replaced the battery, both cables, voltage regulator and changed all my fusible links. Mine is an 81 F-100 and 2 pats of the gas pedal and it fired right up

 

I think you have a bad connection near the battery if you heard a "sizzle".
How are all the connections at the hot lug of the solenoid?
How is the negative (grounding cable)?
Perhaps a bad cell connection inside your battery?

With a new and properly adjusted switch there's no reason for you to lose power.

And the dim lights are a clue that there's a highly resistive wire or connection between the battery and the headlight switch.
Can't you turn on your lights without the key in, or leave them on accidentally?
I know I can, and that makes me think it isn't the ignition switch at all.
Radio memory is HOT at all times.

If the battery is good, then there is an issue between there and your dashboard, or in the ground.

 

I guess my next step will to to add a new batt. I replaced the cables, cleaned and added new ground lug at the block. New silonoid {sp} from ford. the voltage reg is pretty old.
It's just odd that it only happens every now and then, and ONLY when I turn the truck on and try to start it. during my troubleshooting I turn it to on {forward position} and had the lights on to go under the hood to see if there was something loose. Every wire I wiggled didn't change anything with the dim lights until I jiggled the switch /pouned on the column....thats why I THINK it's in there still.......
I gave up tonight....nice COLD 6 pack of Sam Adams and Call of duty 4 to ease my pain

 

The other guys are correct, the headlights have nothing to do with the ignition switch. And turning the lights on was a good clue. Your problem is the battery, the battery cables, or the smaller wiring hooked to the solenoid bat + connection. These and the power distribution splices out at the passenger side fender are the only thing the headlights and the rest of the truck's elec have in common.

I have heard of instances were a battery can have a intermittent bad cell inside it.

 

I drove into the bank one day and hit the speed bump.
Came out and ...nothing.
Dropped a combination wrench across the terminals, nothing.
Plate broke loose internally.
Betting this is the problem, but I could be wrong.
Diagnosis over the internet is like brain surgery blindfolded....