Hard to start 1984 C10

[rhlanham]

My stepson was given an 84 C10 with the 4.1 L6, 2wd. His cousin that had been driving it said it needed a new carb, as the truck would stall out when you came to a stop unless you put it in neutral and gave it gas. Anyway, I got a reman Holley Rochester 2SE and had it installed by a guy who knows what he is doing. Well, the truck runs ok now (doesn't stall), but it does seem like it is running rich. My guy showed me that when you shut the engine off, you can see fuel being burned in the carb. He could not figure this out for the life of him. Also, when starting, you have to crank the engine for 20-30 seconds, then sometimes it will fire, and other times you have to wait a few seconds and try again, and then it will fire. I'm no mechanic at all, but it sounds like the engine is being very sluggish when it is trying to turn over. What recommendations would anyone have as to what I should have checked out? Thanks for your help!!