Rough idle on 1980 f150 4.9l straight 6. Changed plugs, wires, cap, button,vacuum lines...when I come to a full stop it's reaaly rough but when I give it a lil gas it's fine. I simply cannot figure it out.
( also when turning corners the power steering goes out and charge light comes on unless I'm giving it gas while turning.) most anyfeedback would be helpful

 

I would check timing, Fuel/air setting on carb., and base idle, also make sure your dist vacuum is plugged into the correct place. And your carb may be loose, check the base plate nuts. Hope this gets you started.

 

Really sounds like a vacuum leak. Check that the carb is not loose along with the intake/exhaust manifolds are tight to. Those 2 thing are known to loosen up on the 300. Check that your PVC is good and the vacuum line to it isn't leaking. Check ALL vacuum lines at the junctions as well as along the length of them. Carb cleaner or Brake clean work well for that. Just spray it on where the intake bolts on, around the carb and EGR and all the vacuum hoses. If you have power brakes don't forget to spray that hose and the booster to. Just let it idle and listen for any change in the idle. If it does, you've found the leak.