Engine Idle issues

[Blown88GT]

...I also hooked up a vacuum gauge and it reads below normal (13-16 in hg) bounced around in that range.

Vacuum leak, 13-16 is too low at idle.

 

[7991LXnSHO]

Jrichker’s surging idle checklist is where you need to start step by step And in order.
As far as the pressure gauge, I think the one in my car has no core in the Schrader valve. If the glass gets broken when driving, that would be really exciting, so I need to get a core and cap as soon as I am done tuning.
If your car was modified, I would suspect it needs more idle air than the IAC and the throttle plate setting can supply. Similar year trucks had a plate with adjustable screws, or the gasket or IAC wall can be modified for more air flow with big cams.
But the list should get you running great without that.

 

[barry2020]

Definitely appreciate all the ideas. I will try anything. The iac is brand new. TB has a sticker on it it to not clean. Is it still ok to clean? I have had it apart when I changed the egr and iac to semi clean the ports ( without cleaner) and put new gasket on then put it back together. Really just want to know if it ok to clean with TB cleaner? Thanks for all the input

Yes it is ok to clean but you must use a throttle body cleaner, do not use carburetor cleaner. All auto parts store have throttle body cleaner, there is a special coating inside a throttle body, carburetor cleaner will remove it, that is why you have to use throttle body cleaner which does not remove the coating.

 

[7991LXnSHO]

I thought it was because of possibly chemically melting the plastic and electronic in things like the IAC and MAF that the right cleaner is needed.
Either way, it’s a good reminder you put up.

Yes it is ok to clean but you must use a throttle body cleaner, do not use carburetor cleaner. All auto parts store have throttle body cleaner, there is a special coating inside a throttle body, carburetor cleaner will remove it, that is why you have to use throttle body cleaner which does not remove the coating.