T1ZZL3

I know this topic has been discussed, but I have a somewhat different issue. I had my drive shaft and U-joint replaced a month ago because it was found to be warped. This got rid of the vibration and shacking from start to 50. I still have a vibration at 75-80. I have noticed though that this vibration does not occur in the mornings when the air temp is around 76 or below. I have had my tires rotated and 2 of them changed. I am at a loss and the dealership is giving me the "normal characteristic" bull****. It is not a horrible shake but I would like to at the very least minimize it. Any thoughts on this?