Building your own coil isn't the solution. It is a fruitful exercise and a great way to lower costs, but it will not fix your issue. Please be aware of this.
Since it hasn't come up yet, and you've mentioned your tendency to torque the hell out of all your connections, have you looked at your MVP's centre pin? These things are notorious for dropping down with overtightening and a poor connection with your positive pins will cause the exact issue you're describing.
If you have a small flathead screwdriver, power down your MVP and use gentle lateral nudges as you work around the pin. It will start to rise up and may be the simple solution you're looking for. Try to avoid really wrenching down your atty to the box.
P.S. I'm making an assumption here that the MVP3 still uses a floating pin.