ECU questions

[cinman]

I noted when my ECU was last "out" and plugged into a computer, that it wasn't "remembering" faults - it was registering them, then losing the "fault" straight away. Is this normal? Could it possibly be a faulty ECU? I notice they're pretty much solid-state, so reckon there's not much to do to a broken one else replace it.
Also, is there a way to "chip" the ECU to get a little more power out of a '97 4.2? (I know, it's already a beauty, but it doesn't hurt to have more does it ;-)