vibration at sixty MPH

More than likely this is a tire vibration from sitting for so long. What happens is they get flat spotted from sitting on the same spot of the tire and the rubber literally gets flat.

Normally this is felt at all speeds if they are flat enough but if it is not then just at higher speeds.

I would start with inspecting the tires for flat spots or uneven wear. If you don't see it then you are going to need to have them balanced on a machine called a road force balance machine. Basically this puts a roller to the tire and simulates the tire driving down the road to see if there are any vibrations rather then just spinning the tire to measure it which will not show these types of vibrations in most cases.

https://www.2carpros.com/articles/how-car-tires-work

Let me know what questions you have on this and what you find. Thanks

all new tires computer balanced and front end alignment . I apologize for not including this earlier.

Okay. That is good info. Did you have this vibration before the tires or were they replaced in attempts to fix this? Just because they are new tires doesn't mean they don't have vibrations so we need to make sure.

If they check out then we need to look at other drivetrain components like axles or other rotating components like hubs and rotors.

Okay, the rotors possibly all the suspension and axles are new. It only vibrates in the engine not suspension when going up a slight hill or accelerating when coasting smooth as silk someone mentioned a harmonic balancer ? I looked and was thinking engine mounts. I'm just researching i can change plugs oil that's about it.

Oh. I understand. It could be a balancer issue but that normally doesn't care about a hill or not.

Does it feel like a misfire? Can you hear any rattling when it does it? It could be detonation if you do.