when i installed the 454 TB i did not reset the iac per the steps Grumpy described. i confirmed the steps in win ALDL and i saw "0" so i assumed it(pindle) was fully seated and appears as such visually. idle conmmanded at 750 yet will not idle down below 800. commanded 700 stays at 800. i assumed this is due to TB being 454 and engine is a 350 so the non-adjustable throttle stop screw/ butterfly is cracked enough to feed a 454 cid at idle. plausible?

 

What's the idle vs voltage table settings?.

Pausible?, yes.
Non-adjustable?, or the plug hasn't been removed, yet?.

If you've driven it some, and restarted it, the IAC has gone thru the reset.

 

What's the idle vs voltage table settings?.

you refering to the tps? i recall .45 V that too non adjustible and spot on. using TC as tuner.

if that is not what you mean i have the iac steps set to "zero" as a minimum. for what that is worth.

the plug was stubborn so left it in. a drill could not penetrate? will attack with dremel if need be.

yea drove it a couple weeks.

 

What are your int and BLM's? Sounds like a possible vacuum leak as well.

 

i can double check vac leaks but used new felpro manifold gasket and new delco TB gasket. TB is new(1995-1996) so shafts cant leak. will look at vac lines. if that throttle stop screw is set to 454 cid specs would not it stand to reason a 350 needs less air at idle assuming iac is zero steps? like 20% less? i will get dremel out and remove the tamper proof fitting!