I find it hilarious that OP buys a vehicle with known problems and clearly neglected, goes to dealer to get rapped for a diagnostic charge, then complains that the 35d is "delicate"!

I just ran my 35d for 200+ miles towing a 62 International Scout on a full size trailer cruising at 70-75 in 100+ degree weather without skipping a beat. I'd say it's hardly delicate.