Erratic idle '87 Chev injected 383..

'87 Chevy pickup with a built 383 with TBI, TB spacer, Jet chip... My idle used to vary just a little bit once in a while.. Usually would jump up to about 1400-1600 whenever it felt like it, but I'd shut it down and restart and it would be fine. I saw that my temp sensor in the intake was corroded inside the plug, so I cleaned the contacts and replaced the sensor. Problem solved and ran fine for 2 days, but now I start it up and it's fine for a mile or two. Then the first stoplight I come to the idle is crankin upwards of 2 grand. And when I take off it'll studder a bit at times until I really put my foot into it.. Unplugging the TPS and other various things has little to no effect other than what they normally do when unplugged. Can't find any vacuum leaks, or bad electrical.. Isn't that temp sensor the only one that controls the EFI and the other one is for the gauge? Is there something else that would cause idle variations?

Yes, the temp sender in the manifold is for the 'puter and the one in the drivers side head is for the gauge.

May want to look at the IAC on the T/B.

I was curious about the IAC.. I don't remember now.. Is there a way to test those? I love the way this thing performs with the injection set up like it is, and the mileage is great, but I'm sick of the inconsistancies.. Really thinking about going old school with a carb.. I hate this electronic garbage even tho it's a pretty simple system.