Engine missing at cruise RPM
So I drove the car yesterday and I am getting a pronounced bucking/misfire at cruise RPM, tach isn't working currently but its from off idle to maybe 3000. It is most noticeable at steady RPM's... Was going to see if anyone had any suggestions, I will be going through the cap, rotor and wires to check for ignition issues. ALso my Holley 750 has not been rebuilt in at least 15 years so it could be the culprit. That said I am looking for a rebuilt quadrajet if anybody has one at a decent price. There are a few on ebay for 175-200 already rebuilt but they are for 1973's and I wanted to make sure they would work. Ideally I would like to procure the correct 400HO auto carb for 68 7028268.