...fuel injected 4 cyl? what would make my 94 jeep wrangler yj 4 cyl 2.5 liter fuel injected engins stall out and backfire when it gets to 3000 rpms and not want to rev up higher. this happens only when driving. when parked it revs up fine. ive replaced O2 sensor, coil, tps, map, fuel filter, distributer, plugs, fuel pressure regulator, it has new plug wires. the computer says ac clutch relay or curcut #33, O2 sensor reading rich #52(which i just replaced today) and vehical speed sensor or circut #15 are the only codes. any help im stumped. thanks