Timing and Idle trouble

[Zephyr]

Hello! Im new to posting on this site but have found it very useful thus and far, but im finally stumped.

I have to admit right now im the most engine savy but am generally mechanicilly inclined.

So to my question.

I have a 350 small block in my pickup with a standard Rochester Quadrajet in it (sad i know but funds are a tad lacking) and it has been having trouble with stumbling and just bad gas milage as of late. I thought it was the carb and had it rebuilt by a friend has rebuilt carbs like this for years. It helped but didnt entirely fix the problem. I put new plugs and wires in which were generally pretty messed and needed changing anyway, and that didnt help either. Ive messed with the idle and mixture setting and think i have narrowed it down.

With the mixture screws turned allt he way in the engine still runs strong and when i mess with the idle screw i have to litterally pull it all the way out to get it stumble a little bit. So im thinking it may be a timing issue. If not i fear they may be something much worse wrong. Im not pretending to know what im doing i just need help