Here is some insight into the problem, at least from my perspective.

My new RAMPS won't be here till tomorrow so today I completely dismantled the machine's wiring and rewired it. I didn't find anything suspect. So, I fired it up and amazingly, it printed a good sized print for the first time in 8 starts. The motors of the x-carriage were noisier than usual and I immediately suspected that my liner bearings were going bad or something. I lubed everything nicely and tried again. Still noisy.

Part of my rewire was to pull all the stepper motor driver boards and put them back in a different order. I went on the internet and found an article about adjusting stepper motors. It suggested turning the pots down to the very minimum, manually set a travel in gcode and start turning the pots up until the motor started to run. They also said to overdrive the motors until they shutdown due to thermal overload and mark that spot on the board. I couldn't get them to shutdown though. So, all of my motors ran fine at the lowest amp setting. The Y-carriage was a bit weak. I could stop it easily by holding the bed. So, I turned it's put up the tiniest bit. Now when I grabbed it, it couldn't stop it.

Next I set up a print and the printer is much quieter. It was never loud, but it was sometimes noisy. Now it purrs. It appears I was overdriving all of my stepper motors even though they were set at 1/4 of the range by default. I'd say at 1/8 on them right now. However, this print failed and the printer just stopped after about 5 minutes. Drat.

I went back to the RAMPS to adjust pots and felt it. It was pretty warm. I've never had it warm before. I think the dual head rig that I just finished this week is causing it to run hotter. I put a 60mm fan on it and started a new print. So far so good. I think my stopping issues were a combination of overdriven steppers and an overheating RAMPS.

I'll post more as things progress.