1986 305 runs like crap

Hi: I've got a 1986 Firebird with a 305.

When I got it it ran fine for about six months, But now, not so much.

It started to miss, lose power backfire and die while I was driving it and than restart and run like crap. Than it got almost impossible to start. So far I have changed the cap, rotor, cables, ICM, pick up coil, and computer and no change. I will run really bad with the computer unplugged, super rich that is, but now I'm lost. Help please. The way it backfires makes me think the timing is all over the place but the running rich, like 5 mpg rich, has me stumped.

This a electronic fuel controlled Quadrajet, no? Any check engine lite on?

Yes a CCQJ, computer controlled quadrajet. And no check engine light and no codes, well I can't swear to the codes I need to count the flashes and look them up and I loose patients.

Running that rich can be many things, MC solenoid in the carb, bad egr kills vacuum cause it to run rich, lots of vacuum hoses and valves on that engine, you really should get a good manual and go thru the trouble tree, no quick answer to this over the net.

Thanks I was afraid of that.
Like I said it ran well when I got it and than it just started getting worse.
It seems like both fuel and timing which is why I started on the distributor.