I recently started an internship which is about 20 minutes away via interstate. After driving 65-70mph for that amount of time, my 91 Civic STD's idle surges/bounces when at the first stop I come to. The odd thing is, when I turn my headlights on and off, the idle stops bouncing. Is this a grounding issue or something else?

 

If I make this trip with my lights and/or radio on, I don't get any surge/bouncing. What's going on? Electrical stuff is not my forte.

 

I suggest you bleed your coolant and check for any vacuuum leaks
Does it do it when cold?