89 gtu will not idle but will stay running by staying on the gas
 

I redid all gaskets from the top face of the LIM to the air filter today and eliminated a vac leak that caused the car not to run. Now I am able to get it to run by shorting the 2 pin fuel connector on the right strut and by keeping my foot on the gas. The car will not idle on its own and I have tried messing with the idle screw but no change. Without the fuel pin shorted the fuel pressure drops after roughly 3 seconds and the car stalls. For context the car is an 89 GTU NA and I have just rebuilt the engine.

I tested and cleaned the BAC and it makes a click sound and the solenoid actuates about 3/8 to 1/2 inch and has a resistance of 11.8 ohms which is within spec. The AFM is used but is within spec by measuring the resistance. I have tried running the car with the AFM and TPS sensors unplugged as well with little change. The fuel injectors have been cleaned and tested professionally about 6 months ago as well as a new fuel pump about a year ago

My thoughts are either old gas which is an easy fix I will try or something to do with the BAC. Any thoughts are appreciated. Thanks!!

first, are you 100% you have no more leaks?

is there a relay in the S5 fuel circuit? if so, have you tested it?

also, have you tested the temperature sensor in the back of the water pump?

I would like to think I am sure on no leaks but if a vac leak could still be the cause I can dig deeper down to the LIM. I sealed the intake from the LIM up with gaskets and a bit of RTV silicone so there is a tight seal there

The fuel pump resistor relay has been removed and hardwired to the high voltage setting. With the test connector shorted I am achieving the just under 45 psi so 3 bar of pressure. On startup it has the same pressure its only after 2-3 seconds where the pressure drops without the test connector shorted

the temp sensor connector on the harness side is chipped in places but is certainly still in contact. I have not tested the temp sensor itself though. Does the temp sensor have any interference with the idle?

that temp sensor affects idle mixture and it can affect starting, so it's worth checking. i'm not 100% convinced that it would be the only thing at play with your issue though.

I've seen a lot of vacuum leaks come form the LIM/Block gasket.

update:
I added clean gas and topped off all fluids. I removed the tube from the BAC that leads to the intake piping and plugged both ends. This for some reason stopped the car from horribly smoking on startup and my revs were able to sit around 1500 without sputtering. Does this indicate a bad BAC? I had tested the resistance and it was in spec as well as the solenoid actuating with 12v applied. I am happy with the reaction of blocking the airflow but I am just confused.

After this I still have to fix my fuel pump cutting off after a few seconds after startup. I have to keep the 2pin connector shorted for it to run. If there are any ideas on this I would love to hear them.

Thanks all!!