I have 1985 Pickup with a 22R engine and I have had an "air leak" problems since May 2019. It started as a rough idle and it would die if I did not give it gas or if I braked suddenly. This happened right after an Ignition Interlock device was installed and the idle issue has remained long after the device was removed. I have no idea what they could have done during install to cause this problem but the truck ran perfectly before the device was installed.
Currently, it idles alright after starting, RPM's drop a little bit at first but once it warms up it is more or less okay. However, when I come to a stop the RPM's drop suddenly and the truck dies. This braking phenomena has been a constant since the truck first started having problems. If I put any kind of pressure on the brakes the RPM's drop rapidly. I cannot figure out what could be causing this. The truck was initially diagnosed with air leaks and a faulty carb. I have been through multiple carbs (3) and fixed all diagnosed air leaks but the problem persists. My only guess is that there is that the float chamber in the carb is overfilling when I brake but how is that possible with 3 different carbs?

Any ideas on what the primary cause could be for these issues would be greatly appreciated. This truck is eating me alive but I love it and have to fix it.
I have replaced:
Carburetor (3 times + gaskets)
intake manifold gasket
rotor
distributor cap
plugs
clutch plate
fuel pump
fuel filter
radiator
alternator
brake lines
multiple air and gas lines

 

That's usually an issue with the power brake booster or the hose leading to it. I've been thinking about this hose on my 85 and another aging vehicle we have. I would like to know if and how others have replaced it because it's one of them preformed hoses and don't think new ones are available. Start there and good luck. Hope you get it sorted out.

 

Junkyards are the best bet for that hose.