1991 TBI 350 chokes out/dies when I cap PCV port on Throttle Body, help me troubleshoot!

[RockBottomRacing]

So I’ve been chasing down the cause of my high idle condition, I repaced my PCV valve and hose. While trying to diagnose I capped my PCV port on the front of the throttle body, engine instantly died and refused to fire back up. When I uncapped cracked off lickity split. Curious if that is a normal condition? Can anyone help advise me pleaaaaaaase? Thanks guys!

 

[shady]

Can't remember if the TBI has an idle air control valve.. but I'd start there.

 

[RockBottomRacing]

In case others are interested:

My IAC was already new with an ACDelco unit, I did the relearn procedure, no change. Originally I had a LOW idle condition and it would die if I idled in reverse and turned the steering wheel to back in my driveway, a new MAP sensor fixed it, resulting in a racing high idle instead, so I changed the IAC. I ended up finding that two of the wires on my IAC harness were burned and making contact with each other. I separated them, I stripped the burned sheathting off and cleaned the wire with emery cloth. Then wrapped them both individually with electrical tape, BAM starts idles runs drives great. Now if I unhook the PCV hose from the TB she idles high, and if I plug/cap the port on the TB it idles perfect.

Just wanted to share

 

[RockBottomRacing]

Can't remember if the TBI has an idle air control valve.. but I'd start there.

Thank you for your reply! I went back and found wires burned on the IAC harness, I had already replaced my IAC with a new Delco and did the relearn process lol

 

[RockBottomRacing]

Welp! Now my idle dropping and truck dying while idling and turning the wheel has returned… bout to pull some hair out! Any ideas guys?