[EmptyGarage]

I've read the threads that discuss idle issues but they are all centered aroud CIS systems. My engine has been converted to EFI and I need to track down the cause of stalling at idle.

The car idled fine for my first year of ownership but after winter storage I’ve had a issues this summer with stalling at idle. Initially car idled at about 900 rpm’s

Chronologically things progressed as

At first of summer the car started fine and would idle fine so long as accelerator peddle was not touched (knowticed idle speed had dropped to 750 rpm’s) Reving car even a little would cause car to stall once it was allowed to idle on it's own. Moving car out of garage to driveway was enough to cause the car to stall when allowing to idle on it own. Re-start the car and it would idle on its own until warm and then it would be fine. If anytime before car was warn you revved engine...car would stall if left to idle on its own but on re-start would idle fine.

Move forward a few drives. Car takes longer to warm and when driven at night with low ambient temperature car never seemed to idle without stalling. I could still start and car would idle so long as I did not touch accelerator.

last drive. Took on highway drive and car worked fine on highway. Car would not idle reliably even after a long highway run and full operating temperature ( 1/3 mark on temperature gauge). I say reliably because I stopped in a parking lot to let wife out and while there, and after some peddle work, the idle did settle at 750 rpm’s and worked fine (10 min) . At that point I put headlights on and that started “idle hunting” where rev bounced from 250 to 1500 rpm’s until it stalled. Car would stall at stops before pulling into parking lot and rest of drive home. I could keep car running by heel-toe accelerator.

One last observation. The exhaust used to pop significantly at decel but that seems to have stopped as of my last drive.

No engine or other work done to car over winter. Because car idled fine last year I’m thinking a vacuum line is where the problem might be. I’ve seen vacuum diagrams from CIS cars and I’m wondering if what vacuum lines would still be used on a EFI engine and if WUR would still be part of the system.