cutting out

We have a 1995 YJ 4 cylinder. It cuts out at high (3800-4000) rpm. We've replace fuel filter, coil, rotor, wires, and plugs as well as the throttle position sensor. I've heard that it could be the crank sensor and fear we may be floating tired valve springs. Any ideas would be appreciated.

Help. Had my 04 Jeep rubicon in the shop three times. It will run fine for a day to a week, then start cutting out and the speed odometer goes crazy from 0 to 100, back and forth. I have changed fuel pump, cleaned tank, new plugs, shop put in two injectors, they say it shows no codes and does...