Engine Warm stall out

[Swiftler1]

I just got an E 303 cam, Edelbrock upper and lower, 1.6 rockers, heavier springs, 70mm accu fab TB installed. Now all the sudden once the car is warmed up and I’m either down shifting from 2nd into first (slowing down to stop or turn) and the car gets to under 1K RpMs with the clutch engaged it just plummets and stalls out. It’ll start back up but it’ll only stay started with me feathering the pedal. Anything higher than 1K and while I’m driving I notice no changes , also while it’s warming up at idle it seems fine, this only happens after it’s warm and I’ve checked for vacuum leaks already and can’t find one as of yet but did find this piece laying in the engine bay next to the brake cylinder.

 

[General karthief]

Vacuum line for the fuel pressure regulator?

 

[Swiftler1]

Vacuum line for the fuel pressure regulator?

I’m not sure, nothing I’ve seen seems to be missing this short vacuum line but I know it goes somewhere and I do have the FPR vacuum ran over to the intake manifold for sure

 

[Swiftler1]

Can anyone tell me exactly which nipple on the back of the intake the FPR hose goes to by feel from the passenger side of the car? Maybe I have it in the wrong one but I’m not sure that’s possible

 

[General karthief]

Well as long as the fpr has a source by it self (meaning no T to something else) you're good.
did this combo run good and the problem just developed or not run good since it was put together?
either way There are a couple things that could be wonky, vacuum leak, base idle too low or the left headlight is out of adjustment but to save time and money I would run through the

Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

forums.stangnet.com

It was put together by a guy that is tons smarter than me and I will till you from experience it works.
Just start at the top, read it through once to get the jest then do it step by step.
Post up here any questions and of course what it was that fixed it.

 

[Swiftler1]

Well as long as the fpr has a source by it self (meaning no T to something else) you're good.

Thanks

 

[General karthief]

I edited my post, some days I just have more to say