Hi Angela, Just read through your thread, and thought I'd offer my opinion. I've got a lot of experience with Holleys and tuning in general. It's a shame your not near Philadelphia, Pa as I'm sure we could get you straightened out in short order. It's really hard to diagnose a car without seeing it firsthand, but here's a few things to consider......
1st, about your trans question, although it's possible that you could have a converter issue that's causing it, It's HIGHLY unlikely with a C6 like you've got. It's more prevalent in newer cars with a lockup clutch in the converter but it's still rare.
Although it's possible that it's an issue with the ignition system, that's also highly unlikely, assuming the car idles in park.
As for a Vacuum leak, since you have 17" of vacuum at idle, any leak is pretty small, and shouldn't cause your stalling.
A couple questions,
Does your car instantly and abruptly stall as soon as you put it in gear, or does it kind of stumble first ?
If you bring the RPM's up to about 1500/2000 then put it in gear, does it still stall ?
Can you drive the car, if so, how does it run at speed ?
Since it's kind of pointing to a carb issue, Here's a few things to check...
Do the mixture screws seem to affect the idle ? , will the car stall when you run one or both screws all the way in ?
I'd back the screws out about 3 turns or so and se if it still stalls. 3 turns should be pretty rich, but your car won't stall because of this and it will rule out the mixture adjustment.
Holleys are pretty simple, basic carbs, but they can still drive you nut's if they have issues..
If the car' still stalling in gear (and it's a carb issue) it's either really lean or really rich. Really lean could be caused by an internal carb issue but that's pretty unlikely. Because closing the choke (or cupping your hands over the carb) doesn't change anything and you get some improvement and an increased idle by cracking the secondary's, they both point to a REALLY rich carb condition. This is usually caused by one of two things on a Holley, Dripping boosters or and internal leak.
1st, start the car and look down the carb throats. see if you can see fuel dripping from the boosters onto the throttle plates. If you do, it's usually caused by your float adjustment being too high. Other causes can be a needle/seat issue, a float issue (binding or full of fuel), or fuel pressure too high.
If you see no evidence of fuel dripping from the boosters, I'd highly suspect an internal leak into the power valve well in the main body, either from a blown power valve (unlikely) or a warped metering block or main body (REALLY common on older Holleys)
If you're not comfortable with taking your carb apart, I'd try and borrow a known good Holley just to make sure your carb is your problem, then send your carb back to whomever rebuilt it or to a known good carb guy..
If you are comfortable in dissembling your carb. Drain the front fuel bowl into a cup or rag by removing a lower bowl screw (you can leave the carb on the engine.) carefully remove the front bowl and the front metering block. You should see a well (recess) in the carb body where the power valve sits. This well is connected directly to manifold vacuum and any fuel that leaks into here gets sucked directly into the engine. The well should be dry, If it's wet, either the power valve is bad, not common, or the main body or metering block is warped. This is REALLY common with old holleys, as when the gaskets get old and leak, people tend to get king kong to tighten the float bowl screws to try and stop the leak. This causes the 4 corners of the main body where the bowl screws thread into to bow up and fuel to leak between the block and the main body and get drawn into the engine. You can check the main body and the metering block with a straight edge. If the block is warped, find another one, if the main body is warped (LIKELY) You can either have it milled flat, or spend about 1/2 hour with a sharp, wide, fine flat file and do it by hand. You'll have to take the carb off the engine, completely disassemble it, and clean it really well afterwards. Use a new power valve and a new power valve gasket.
At least 1/2 of the old Holleys I rebuild have at least some degree of distortion of the main body, warping a block is uncommon but you do find it occasionally.
Once you get the stalling thing fixed, you can use your vacuum gage to set your mixture screws. Start with 1 1/2 turns out and adjust each screw for the highest vacuum reading.
Let us know how you make out,
John
BTW, If you do find out your stalling was caused by your carb dumping fuel into the intake, make sure you change your oil, as a lot of the fuel will end up in the pan...
