I have a 92, gmc,k1500 pickup, v-6 fuel injected with the following problem-After engine warms up, it runs rough and misses under load(accelerating) I have changed the plugs, dist. cap and rotor, plug wires, coil, and fuel filter. I have had the "check engine" light come on periodically, but it only stays on for about 10 seconds and then goes off. Any ideas? Thanks