That carb has a lot of crud in it, much more than mine did so yep you need a good soak in an ultrasonic cleaner or soak it in old school carb and then (put on goggles first!) blast out the passages with compressed air. One area that is a problem is the idle air tubes these can be tough to get clean if the carb was left with gunk in it. The Q Jet has both primary and secondary metering rods that have to fit the jets properly and those jets must be clean.
I have never seen a Marine QJet with an electric choke, but if you have one, it has to get 12V any time the engine is running or else it won't stay open.
I may have some pix with all the passages labeled for the QJet, I have to look and see if I can find them....
As you can see it is a fairly complex carb, people like me who started working on cars in the '70s are familiar with them especially if you had GM cars in your family, they were used on just about all the V8s from 1966-1986. The high performance versions did come with Holleys, but the Quadrajet was pretty much ubiquitous on GM V8s.
