Engine stalls in gear

This is my first post so bare with me, will post in welcome thread soon.
Just wanted to say that i had a the same problem with a OOTB Holley carb because it had a 10.5 power valve that i was unaware of. My in gear idle vacuum was around 9lbs. Switched to a 6.5 and the engine cleared right up. Just something to check if you have a new carb?