Idling engine while towing questions

Towed my 1993 Ford Taurus for 2 years with the engine running in neutral. Never a problem and it got 100 miles to the gallon. Tested it first in the driveway, let it idle for two hours, never got hot because the electric fan comes on. Since I use a Brake Buddy, I installed a 3 way valve in the vacuum line to the power brake booster so I could vent the line so it wouldn't be power brakes when the engine idles or the brake buddy would lock them up. No problem with the power steering so far as I could tell, tires wore normally. Alot cheaper and easier than installing an axle disconnect for $1000 dollars. On the Taurus, you have to lower the sub frame to remove the front sway bar to shorten one end, weld it up and reinstall, not a simple job.