a have a 305 non computerized engine it first started out with my trani siezing up, i changed it out and it helped but now i still have a problem i dont know what it is but when you start it it trys to die unless you hold the throttle for a min then it stays at idle but it jumps up and down a little bit but when you throw it in gear it dies, ecspecialy in reverse but once you get going its fine, other than the slite hesitation under 1500 rpms. now i checked the spark its fine, i checked the fuel, its getting to the carb and in to the intake and i checked all the vaccume lines, there good. any ideas?

 

What is the idle set at? Have you tried turning it up? Once the car is running and driving, say on the highway does it stay running? If so, does it die when you come off the highway and slow down like coming down an off ramp? Otherwise does it only die once you put it in gear? I'm having similar issues with mine. Your carb may need to be rebuilt as this sounds like you have a vacuum leak inside the carb which is preventing the car from getting fuel at the lower idle speeds since it's not pulling enough fuel through the idle circuits. I say similar to mine because I put a bigger cam in with only 9" of vacuum so I would only pull enough fuel once the carb came off the idle circuit. since your car is more stock than mine, I would tend to believe it's internal to the carb.