I just installed a 355 in my 84 monte carlo but i took out the ecm and am currently using a 1976 vacume advance distributor. when i go at a steady 2500rpms (55mph) my car seems to surge back and forth just a tiny bit. like it needs either gas or more air idk? im also thinking it may be the distributor. i replaced the weights already. i have already hooked a vacume gauge to the carb to make sure the jets are tuned to the highest vacume. there are no vacume leaks. is it possible to test the vacume advance with a gauge?? i dont have a timing light.HELP ME Why is it surging?????