1978 Nova acceleration problems

I have a 1978 Nova with the 250 and the single barrel carb. I recently rebuilt the carb to spec and replaced the fuel filter because drivability issues pointed to that.
Those issues were hard to start. Main issue ended up being a ton of varnish in the carb and a clogged fuel filter. All of those issues have been solved but I get a huge hesitation and stall when the car is in gear.
In park and neutral the car performs as it should and has perfect throttle response. The timing is dead on, plugs are good, wires are good, and everything else seems to be in order but the car just doesn't want to perform at all when it is in gear.
Any ideas of what is causing that? I ahve been trying to chase this down for a while and have hit a dead end. The choke operates perfectly, the float is set correctly, and it starts and idles and revs perfectly... As long as it is not in gear.
Thanks for any help!

It sounds like the car has been sitting around, so I'd suggest that you check your rubber gas lines to see if one has collapsed, is cracked or very soft. Go from the fuel pump to the tank.

If you can get a new or rebuilt fuel pump easily enough, change it. You may not be getting enough fuel to the carb. If you want to do a fuel pump volume test first, which you should be able to find in a Chiltons manual. It involves removing the fuel line at the carb, run that into a jar and cranking it over (coil wire removed) and see how much gas flows for a certain time period.

Bob

well looks your in the same boat l have the inline6 to
l had stalling problems with mine, in gear or at a stoplight
plain and simple my car had low tranny fluid and had sat for 5years now after topping the trans off several times and goign threw the gears and driving around it functions fine

Tranny fluid low