What would cause my car to have inconsistant vibrations at higher speeds? If you read my last post you know that I discovered a missing lug nut. After replacing it the car seemed to run like a charm. At least on back roads. Yesterday I took a long highway drive at 70-85 mph and a vibration would develop sporadically. I could go 10 minutes smooth then vibration for a few minutes then it would smooth out again. I would think that a tire out of balance would vibrate all the time. Could I be wrong? I read the other post here about drive line vibration, but his scenario was different.

I had the same problem with my car when I first got it. Try replacing the spark plugs and wires, you might have a fouling out spark plug making you run on 3 cyl at times (which was my problem, then I managed to break a wire boot in the process too lol)

I had the same problem with my car when I first got it. Try replacing the spark plugs and wires, you might have a fouling out spark plug making you run on 3 cyl at times (which was my problem, then I managed to break a wire boot in the process too lol)

Thanks for the reply. That's an interesting concept. I have a set of NGK's sitting at my auto shop right now. They're waiting for me to bring it in. I'll let you know the outcome. In the meantime I'm getting my tire rebalanced just in case.