Anyone ever experience this

Ok so has anyone experienced this before. My 73 dart when you turn the ignition and put the car in gear - cold or warm it feels like the gas is sloshing around in the tank and then it feels like the brakes are dragging - I’ve already had the brakes and the parking brake looked at twice and the first time one wheels brakes were holding and the second time it had to do with the parking brake which is disconnected now. I Still have the problem and it is extremely annoying to drive like this. Any ideas as to what is causing the problem thanks

The car has a 225 with a rebuilt transmission
How long ago was the trans rebuilt?