So I have been chasing this issue for abt 2 weeks, it ran perfectly before I changed my lower intake manifold gaskets. After finishing I got to start it it cranks and starts up it sometimes shuts off shortly after starting (1/8 cold starts) but when it does turn over it goes between the 30 and 35 marks searching for a stable idle. I have smoke tested, with all vacuum lines on and off and to no reveal I so far have replaced PCV valve and gormmets,IAC,the small T under the tb, new tb gasket, tested voltage of tps, all throttle lines are to spec, spray tested couldn’t tell difference, double checked egr valve and gasket and throttle blades, cleaned the tb and to no change… I’m stuck at this point everything points to vacuum leaks or openings. Any idea what’s happening? Any ideas help greatly. It’s a 1987 iroc-z Camaro with 305v8 tuned port injection (video is @ 2x speed)

edit: when giving it gas it does what it should

 

Temporarily plug the PCV, brake booster, and canister purge line.

What intake gasket set was used as a replacement (manufacturer and part number)?

 

After a LIM gasket job, I’d re-check gasket alignment and torque sequence, especially the china walls and intake sealing around the runners. A small internal vacuum leak there can cause exactly that idle hunting.