Acceleration stalls engine

I recently bought a 1962 Corvair 700. Yesterday the car started having a problem, when idling or very light accelerating the car operates fine but under any push of the accelerator harder than a light press will make the car stall and shut off. There also is a strong gas smell coming from the engine bay and into the inside of the car. I've looked and I have yet to see signs of a gas leak. My uncle suggested it could be the carbs are flooding the engine. The only thing is it only does it when it's in a drive gear(it has a Powerglide) in neutral I can rev the engine with no problems. Also the guy I had purchased it from had told me it was running rich. It seems to only do it after extended driving, yesterday I drive it a few miles to get an inspection sticker and to warm up the transmission so I could check the fluid. I tried it out today and it did not stall and accelerated fine. Any help you could give me on this would be great, feel free to ask if you have any questions. Thanks!

Webers or Rochesters? Either way, the float levels need to be verified, and both carbs should be checked to verify proper operation of their accelerator pumps.

Weak ignition energy can also cause stumble under load, and that can be due to generator/regulator problems or ignition problems.