Mountaineerfan

Ding Ding Ding!  Free beer for Mach1 Driver tomorrow!

BTW, found the major culprit.  
While doing work in the engine compartment, I (or someone working with me) had somehow pulled the wiring harness away from the shock tower, and it had touched the exhaust manifold bolt.  This managed to burn a small section of the harness, and fused the left turn signal wiring to the wire leading to the solenoid.  It took a long time for me to find, as the spot was on the bottom of the harness and not visible upon looking down at the wiring.  It wasn't until I actually grabbed the harness that I felt the burnt spot.  So some wire splicing later, it's fixed.  
Yeah, hitting the left turn signal kicked on the starter, but there was no power to the coil, so it didn't actually start, just kept spinning.

Donated!
This site has helped me so much.  It needs to stick around for others!!

Yep that is showing a splice

Thank you!  So 2315 is what mine came up to, so I'll stick with the 2000ppm setting, as it's the closest.
 

Let me take a shot...
Measure your tire diameter in inches:  D Calculate tire circumference:      C = (pi * D) = (3.1415 * D) There's 63,360 inches in a mile.  (12 in/ft * 5280 ft/mi)  So tire-rotations-per-mile = 63360/C Finally, your 3.00 differential spins 3 times per tire rotation, so the driveshaft speed is (3*Tire-rotations-per-mile) Example, tire is 24" in diameter...
D= 24 C = (3.1415 * 24) = 75.6336" Tire-rotations-per-mile = (63360 / 75.6336) = 837.72 Driveshaft-rotations-per-mile = (3 * 837.72) = 2513.19  
[edit] Maybe easier just to measure your tire circumference instead of doing it the long way?

I am WELL acquainted with those boots!  I chased a rattling front-end noise for YEARS, tightening everything I could get a wrench on, replacing everything rubber I could find.  Finally, someone here mentioned to me to check those insulators, and lo and behold all of them were missing!!  What a pain!  Since this was my first Mustang, I didn't know that they were supposed to be there!  So yes, those have been replaced!  
Is it possible that the pins are sticking slightly, causing the flex in the caliper?  I lubed them when I replaced the brakes, but maybe not good enough.  I also had to take a razor blade and puncture the end of the boot, because the suction was causing me problems removing the pins.

My bad, I must have had my head up my rear that day. Could you not just grind a bit off the caliper where the rotor is rubbing or is it in a place where u can't. I would check the dia. of that rotor tho because if it is  a little oversize that would be an easy fix.

Brahahaha. Airplane. 

I have a sqeak coming from somewhere behind the front seats. After much investigation I found if I turn up the stereo real load the sqeak goes away. 

Hoping to catch a couple of stops, Probably Rockingham and Charlotte.  Don't have any advice for Long Haulers, but there are some groups on FB that talk about this very thing, if you are on FB.  

Yikes!  I have a convertible as well.  I have no idea how I would fit through those little openings behind the seat!  Maybe if I remove the motor....
Glad you got it!

UPDATE:
Replaced the check valve ($8 at AZ).  Totally revitalized my braking response!  Always check the cheap easy repair first!

UPDATE:
Replaced the check valve ($8 at AZ).  Totally revitalized my braking response!  Always check the cheap easy repair first!

UPDATE:
Replaced the check valve ($8 at AZ).  Totally revitalized my braking response!  Always check the cheap easy repair first!

Mine was cracked and it wasn't all obvious it was until I tried to pull it out of the booster, and it broke.  Make sure you get the right size hoses to go with it.  It should go from the booster into the main vac port on the back/top of the engine.  This hose is very important to overall vacuum, as it is a larger size, and leaks have a big effect.  It won't cost you but a little more to get the hose replaced.

Thanks for posting 'the fix'.

Bingo! This was the issue! At one point on the trip, I went to start the car and nothing happened. I reached behind the switch and pressed on the wires in the connector, and tried again. It started fine after that. I just installed a new pigtail, and all seems happy! Quite a bit of corrosion on the old wires. 

Thanks for the replies! The car is a 69. 
While I will check what you all have mentioned, I have another theory that I haven’t tested: When I installed the new starter solenoid, it was a black color versus the gray color of the old one. Since that’s when my trouble started, I looked again at the online descriptions of the starters. Apparently the gray one is heavy duty. Could this be the issue? 
By the way, we made it to Dearborn from Atlanta! The power issue cycles through about three times and then stays on, so we’ve survived the travel. I’m posting on Instagram if you want to see our pics: @stevestang1969

Check the plug on the back of the ignition switch. It is common to have a burnt up connector on the plug on cars with a/c due to the higher current load. Back in the day when you bought a new Motorcraft / Ford ignition switch it came with a new pigtail to make a proper repair.

Sounds like something going on at the fuse box, as radio, backup lights, and blower motor/AC are powered by ACC and fused by 2 fuses.  Might be a bad ignition switch or bad/nearly broken wire for ACC at fuse box.  Usually, it is the BAT line that breaks, not the ACC line.  Something is going on that when more power is pulled through those lines, continuity is lost due to higher resistance.  I'd check your fuse clips first.

Cool, just what is hoped for. A big thanks to you both. 

Through the firewall.  I had the heater box out and that made it relatively easy.  I actually installed a heavy gauge amplifier wire to the battery and to a junction box mounted to the right of the glove box. I then used a relay with the original radio wire as the trigger.

The OEM radio was lit by a single bayonette style bulb that got power through a single blue wire you can see in the photo below. It sounds like your harness is pretty butchered so it may take some work to find the conductor (or what's left of it) in your dash.
 

By the way, above is from memory when I removed it a year or so ago.  Do not force anything if you run into a snag but let me know so I can go look at my 70 vert as trim is not installed on that car at the moment.