I am trying to find what sounds like a large leak. sprayed carb cleaner under plenum around the pressure regulator and the engine stumbled. It is idling very high. took plenum loose and cannot see a problem. I did notice the cold start valve hose off but I may have done that while taking off plenum. any ideas for me to troubleshoot more? thanks
If you have an idle over 1500 rpm, there are only about 3 places that allow that much air.....Brake Booster, EGR tube, and the Throttle body hose that you mentioned. They are all a lot easier to check than intake gaskets.
My 86 gt just had same prob. I used a CLEAN shop vac. And blow into the air intake hose before the TB. Sprayed engine and suspect areas with mild soap and water in spray bottle. Look for bubbles. Mine was in the TB gasket
Go to the gas station and get a cigar, or two. Get a long vacuum hose and hook it up to any vacuum port you like. Light the cigar and start puffing smoke from your mouth into the hose it shouldn't take much the more you puff the easier it should be to find.