So I am going to borrow my dad's 83 300d with 430k on the odo. very clean ride. I am using this yellow turbo slug while I do some repairs on my 82 300sd. When I fired it up today it took a couple of tries to actually run (has't been driven in a week or two) and while idling it started surging slightly, I believe this is called "hunting" it is very rhythmic and noticeable. So just what effect will this have on the old beast(but what a beauty!) and how is it that I go about a fix?
Also high beam indicator and high beams do not work. the normal beams go dark when switch is engaged.

Thanks for any wisdom,knowledge and support . zachariah