surging idle, has to be something simple

[78ak]

I’ve got a 1978 chevy 350 with auto trans – I bought it a few days ago, and guy said its been in the family since 1980, and his grandpa did a “complete overhaul” in 1986, and he got it in 2007, hasn’t been driven more than a few hundred miles since then, and not at all in the last 4 years, but it was in a heated shop. Drove it home, battery shot, died 4 times, stopped and a got new one. Made it home, and saw volt meter only charging around 9 – changed alternator – now pulling 14 or so, working good. Issue is that it used to die when putting into gear. Done a couple small things, now it doesn't die (most of the time), but it runs rough. When driving down the road and coming to stop, idles choppy and way too high.

So far, all I’ve done is put in a fresh tank of gas, changed the plugs, checked all the vacuum lines for leaks (including the brake booster which I thought it would be and the line on the back of the transmission), new vacuum advance, new sending unit for the temp gauge (it was bad), new fuel filter in the carb, turned the distributor about a quarter inch counter-clockwise, and new PCV valve. It idles good. Choke works well, and it kicks down to probably 600-700 RPM after warm-up, sounds good, minimal to no missing. Before I did anything to it, it would die instantly when put into reverse or drive. Now it will sputter a bit but not die every time. This is all after warm-up. If I put into gear while the choke is on, it shifts into reverse and drive perfectly, no hard shift, but it surges from low to high idle. When let off the brake, it will drive at high idle RPM, way too high. I’ve done a little research and found everything from torque converter to fuel pump to ignition control module, to timing, etc. Before I do anything more, thought I’d throw the question out. I know there's a chevy guy out there who knows exactly what it is. Thanks for reading and responding if you have any ideas.