i have a 1973 corvette w/l48 350 stick w/ac.car has 87000 mi and is all original except for headers and i replaced points and cond with electronic ign conversion kit.seems that after driving car for 20-30 minutes and i step on gas,it pops at carb and sometimes stalls.car won't start up right away, but let it sit for 10 minutes it starts right up but has trouble running in gear.revs fine in neutral.next day car starts fine.help