I heard the motor; idle didn't drop when I pulled #5 spark plug. He might have a couple problems. told him to start with easiest to hardest task. First figure out electrical. might be running like shit because he's on 5 cyl. it was rapping pretty loud in the center. Told him to remove the valve cover and inspect and readjust his valves. then go from there.
I suspect his timing is off but when you have 2 or 3 issues it is difficult to assess. Process of elimination.