1974 1.8L engine fast idle then stalls, Fuel injection issues Options

[tshih914]

My 1.8L 914-4 with stock Bosch L?-Jetronic FI after being stored several years started to develop a hard to start problem. When finally started would stall when I give the gas pedal any input to raise the revs. I suspect there was some kind of intake air leak and while fiddling around had a backfire which blew the AF meter which I had Pelicanparts repaired. After replacing the fuel lines with the stainless ones from Tangerine Racing and flushing out the fuel system with Techron the engine started to run normally for a short time. Now the engine can be started and fast idles at 3000 rpm but again any input to rev up the engine results in stalling. The idle adjustment screw at the base of the throttle housing is fully closed. Any suggestions on how to fix?

[r_towle]

When I am hunting for a failure in the vacuum system, which has many parts, I remove all vacuum lines and tape over all the ports at the plenum.

This takes the vacuum out of the triage.
This also takes any hose out of triage.

Get the car running at idle (it needs no vacuum)
Add one vacuum line at a time, plugged into whatever device, properly.

Eventually you will create the issue again.

If you still have an issue after taking off all hoses and taping all ports closed, you could have an issue with a hole in the bottom of the plenum or your injector seals are leaking way too much.