I did a set of OEM 340 AAR Cuda carbs years ago, it was very sensitive to the center carb. jets, one size up or own made it not drive well I didn't look up the carb. # you posted, if it is a original, not a replacement carb with a -1 or -2 to the right of the list number then try looking on Holley web site for the original jetting and start with that, don't forget to use the proper power vave, especially with that dang Mopar 284 camshaft Good luck, I agree with the others on the surging, one step, one Holley # richer jet, not 4 should eliminate the surging Let us know what you do and the results please.