Have had a long line of electrical problems with this 87 302. It finally will idle but high idle. Extremely high idle. But when I unplug the iac it goes down to normal. And when I accelerate quickly the engine try's to die and backfires. But it's hazes black smoke out of the tail pipe. After testing everything but the ecu i use a friends out of a bronco with same engine and it didn't change anything but when he put the ecu back in his truck his has now has the same problems mine does. Any ideas?

 

Bad grounds and/or shorting wires