I have a 91 LX and when I bought it the tach was doing the hop too. I had no driveability troubles though. I found the tack wire (blue) at the ignitor under the distributor cap was loose at the bullet connection. I merely crimpe the connector a bit and have had no trouble since. You may have one or two loose wires at the ignitor. I figure when someone was under the cap they jostled them which would be easy to do. Hope this helps!