Jimmy Tea Kettles, Stalls, Back Fires, Hard Start, won't Run Right!

My son had my Jimmy, a T-15 one day driving down the road, heard a loud boom, and the SUV died, turns over but wouldn’t start, towed to my house, starts hard, you can bring up RPMs if you step gingerly slowly into throttle, and motor dies/stalls if you press with normal push with normal driving force on the throttle. Timing light indicates motor is in time when disconnecting brown wire on the computer which is supposed to disable timing advance.

This Jimmy is a 1995 with Vortex V6, 4.3Liter

I am adding details sorry! Muffler exploded when the loud bang was heard and I blew another one off before I realized the back fire was a permanent problem until I figure out why it wont run!