i have a carburated first gen small block with a stock mechanical fuel pump. the car wont idle after being parked on an upward angle until its driven for a few minutes, but runs fine if you keep the RPM up. both the carb and the fuel pump are only 2 years old but i only drive it in the summer and only about 5k a year. if anyone could give me some ideas as to what this could be, it would be great.