Nissan Repair: Pathfinder AIC, mass air flow sensor, mass air flow

Question
I have had problems with my Pathfinder (02) for about a year now, it will not idle correctly and dies often. The check engine light is on. The First mechanic said it was the Mass Air Flow Sensor so I replaced it and it still didn't run properly, so I bought a new Air Idle Control valve and it ran fine for a few months, then it started again and began blowing the ECCS2 fuse, so we had to put a higher fuse in it to get it home, once home we noticed that the plug to on the wiring harness was melted so they cut the plug off and left the wires taped up the vehicle still ran fine for a few more months. Now it's back to the rough idle, stopping-dieing, no power (you have to just slowly gas it bit by bit and it will go)I've tried everywhere for the wiring diagram or a plug or even the wiring harness Nissan wants $1800 for the harness alone not including labor to put it on. PLEASE HELP THANK YOU ERica

Answer
It is serious when a mechanic cannot troubleshoot a problem correctly and even worse when an engine management component's connector is cut and taped. At this point, there is a number of tests that need to be conducted to find the initial problem that led to this. Please do not replace anymore parts. My recommendation is to find and ASE certified tech in engine performance and he does not need to be a Nissan tech, and let them look at the problem. Replacing original fuses with higher amps ones is not a remedy either because it's obvious that there is a short circuit along the line somewhere which needs to be found. An engine performance certified tech, had also passed his tests in the automotive electrical field. :)