2003 Silverado shudders when driving but then stops
After my Silverado sits for a few days, if I take it out and drive it on the
highway from 55 - 60 mph, the truck begins to shudder. I then get on the
frontage road where I have to go slower and don't feel it. Then when I get on
the highway again, I can go 55 - 60 mph and it no longer shudders. When I
get where I'm going, I can park for a while and still the shudder doesn't come
back when I drive. I don't see any engine lights and I looked at the rear ujoint
and nothing seemed to be wrong. Any thoughts before I take it to the shop?