Could be either one of those, or does anyone else know how much of an effect the IAT has on running condition? As today was a much more cold, damp day than yesterday, and today it ran just beautifully: Steady idle, perfect power delivery, everything!

Also, checked the vacuum lines. All is well on that front.

 

TPS is completely unscathed (Weird, I know), and although the connector for the IAC looks awful, there's no resistance in the circuit. Both of the actual sensors are brand new (They came with the new TBI unit).

I'm thinking that vacuum leak idea might be it. The truck has been shifting hard and late, which would make sense if the modulator is seeing relatively low vacuum at all times.