The 4.0 is a really strong engine. I ran a 75 shot of nitrous on it for two seasons, and then with 90,000 miles on it, pulled the nitrous and put the Xcharger on.
I sold that car in June when I ordered the 2013. It had 203,000 miles on it, and was still running mid 12's at the track. All on the stock engine. The new owner said he is planning to take it to the track this summer and it still runs great with no problems.
Nice Pony over at MustangCollective ran his for 150,000 miles, and the only reason his let go was because he was racing (he does road course, I drag race) with less than a 1/4 tank of gas. On a long turn he starved the engine of fuel and a piston chipped from the detonation of the lean condition.