My 1965 Malibu is very sensitive in first gear and if you try to romp on gas pedal after letting off the clutch it's herky jerky. I just want it to move out. Also if vehicle heats up and I go somewhere car cools down for 30 minutes or so transmission gets in a gear in between and will stall out every time. I don't understand it. Feels like I got ghost in the transmission. Would you recommend rebuilding transmission? What do you think is wrong with it?