I have a 97 4.6 and while I'm driving on the highway going anywhere between 40 and 60, it drives a little rough it feels like I'm getting a massage or something lol and when I'm at a complete stop and I press the gas to go there is this squeaking noise that feels like its coming from underneath the truck where I am. The noise goes away when I get to about 30 but thats when it shakes a little. Any idea what this could be?

 

Could be a bound up u joint, pull the shaft and flex both joints in both directions and feel for any stiffness. If found replace them with good quality parts and enjoy the ride.

 

I'm getting them replaced tomorrow I would do it myself but I'm not very good with that kinda stuff lol thank you sir