i was driving down the interstate doing 65mph when my rpms dropped from 3200 to zero and the car's engine just died out on me. i tried to restart with the choke and got nothing. messed around with the dual carbs tried again and it almost started but the rpms went way up on me to the 3000 range then i got a loud backfire out of the exhaust like a .45 cal hand gun. tried messing with the carbs a little more by hand adjusting them, didnt have a screwdriver, and the same happened again got the loud backfire and could never get the car started. i walked to the nearest gas station bought extra gas and still i couldnt get the car started, had it towed to the house and its sitting in the garage currently. info on my car is a 72 240Z automatic transmission, has a new distributor cap, new plugs and wires,. newer battery and radiator. the carbs were recently rebuilt but where never really synchronized. but despite that the car still ran. just 3 weeks ago i drove it 160 miles on a trip with no problems. battery is good i can turn the lights on. the car is all stock with no mods. transmission fluid is clean and the oil was recently changed as well. i do get a spark , i took the air box off and noticed the air filter was filthy but that cant be the problem, also i cleaned up the air box itself since it was filthy. also there is a hole in the exhaust but that wasnt a problem for me when i took that long trip. im not too familiar with the 240Z as i have only had this car for about a month. i never had this problem with my 91 300ZX