Have an 83 Caprice, 229 with the Rochester Dualjet M2ME. Just rebuilt the carb, now it runs very poorly. Will barely stay running when pumping the gas, coughs flames out the top of the carb. Have not messed with the timing at all and it ran pretty well before the rebuild. Is it running too lean, too rich? I was a little unsure how far to tighten the screw that holds down the mixture control solenoid inside the main body of the carb; could this be the problem? I haven’t touched the sealed mixture screws.