IIRC------there are 128 terminals on the ecm plus several more on an anti/theft? model (body control)
You need to put a piece of tubing on that MAF control valve to staighten flow to it ( maybe just putting the air cleaner eelement on it will help-

One new header??? does it clear the sparkplug wires good because not many headers clear the angled spark plugs------- Knock sensors installed correctly in the right threaded holes???