It seems to come & go. I get P1280 frequently and it seems to 'short out' or something intermittently where I'll get surges of massive power with black smoke, extremely lopey idle, and stalling. I've repeatedly tried wiggling the wiring with the sensor connected and the engine on and it seems to do nothing. If it runs decently with the sensor disconnected and only craps out when it's connected is it fairly safe to say that the sensor is indeed faulty?

 

Yep. If the PCM sees wacky signals you get wacky fueling. If the PCM does not see an ICP signal (harness disconnected) it will use a default value that will allow the truck to run, but the fueling will not be adaptive. Another sign of ICP failure is the top where the harness connects will be wet with oil. If it's oily clean the harness with brake or contact cleaner. Also inspect the wire closely for damage, old brittle wires do not like being disturbed.

Fleabay ICPs are cheap, and included with that cheap price you get a long and storied Reputation for continued Grief and Despair. Gotta go OEM here.

 

I saw super cheap ones on Amazon but I know this is one of those "OE only" parts. I considered a cheapo just to test, then realized that no matter what it does it won't be definitive since I don't know what that $20 sensor will be doing. I just don't wanna blow $140ish on a part I don't need. It was oily, I cleaned it out, no oil has reappeared but I've only got a couple hours on it since cleaning. This is a new purchase and I'm diagnosing/fixing lots of stuff as I go though it.