My bet is the harness. It will affect your injectors and GPs. My was acting crazy as hell. And was very intermittent. Get a harness from Oriely's or advance. And save some coin. Yes they are made in China just like the Ford ones.
The plastic is very brittle so be carefull. So dont waste your time with the $.25 fix. You get the valve cover gasket and harness with the kit. Dont be dumb like me and not replace your GPs while they are right there. I think I paid ike $150 for the kit. GPs are around $50 a set I think. My harness outside of the valve cover seemed to be in good shape. So I didn't splice a new connector on that side. The exposure to all that heat kills the plastic under the valve cover. I could do it now in well under 2 hours. The first time took me about 3. Those rear bolts require a swivel and lots of paitence