Quick run down of my issue that just occurred on my 89 4.3 TBI. Truck was in my driveway idling before work and after a couple minutes started stumbling and dying out. I would turn it off and it would continue running like it was dieseling. The gauges on the dash wouldn't fully turn off either. After a few minutes it started running fine but the idle was super high at a guess 2k+ rpm's or so. So I drive 3 minutes to work and wait for daylight. I pop the hood and close the door and heard my fuel pump run for a couple seconds (no keys). After popping the hood I see that the air cleaner shifted and grounded to the alt charging stud. After pulling the housing I noticed the insulation on the TBI injector connects was melted off. Started the truck again and it fires up like normal but still idling way too high. After work I replaced the TBI pigtails and checked things out the best I could. Everything else seems to be normal and working it just idles way too fast. I checked for vac leaks just in case and didn't come up with anything. I relate this to the short I had. I unplugged the IAC and TPS and that makes no difference other than the CEL comes on. If you unplug one injector it idles lower but then will pick back up again. So I don't know what to check or test next. I don't know if the computer is facked or just a sensor. I don't know if the injectors would be screwed or not. When it's idling the butterflies are pretty saturated with fuel. Almost looks to be too much, but I have nothing to base that off of. I don't want to just start replacing everything if it isn't the issue. Any ideas on what to check and how to test it? Couple pics, air cleaner spacer melted, wire insulation GONE!

 

I picked up a replacement TB unit from a wreckers today. Swapped the injectors and that didn't help. Swapped the IAC which was like new, and that fixed it. I'm just glad it's working again.