From the sounds of it, I don't think I'd be wanting a call back from that particular shop, let alone waiting for one.
The "she sits sometimes for a month or more at a time" comment is very telling. The A4 begs to be used and is most well behaved when she is. Today's Ethanol laced fuel
is creating havoc in older engines, marine or otherwise, because they weren't built with seals and gaskets that were expected to be exposed to that. Couple that with the tough life they lead living in Saltwater most often, and you've got "issues" when left alone. Down here (Florida), I find it best to at least clean my carbs once every year and rebuild them at least every other year. When was the last time that was done on this particular unit? The fuel
system hints have been good ones and you should follow those recommendations posted. I for one, would've assumed the entire fuel
system was bad when they replaced the pump
and had every inch of hose put in new. Good luck and I hope you get someone that can help get her back to chugging as nothing is more frustrating than spending all your time "fixing" and none "enjoying" the boat.