This just started today when my truck is in gear and underpower there is a vibration present that wasn't there before. When you coast in neutral it doesn't to it and if it is in gear but coasting the vibration is much less pronounced than when it is accelerating. I'm thinking it could be a bad universal joint but am unsure what do you guys think.

btw its a 98 dakota with a 3.9 liter and the 5-speed

*edit*
I found it the #2 cylinder wire had loosened itself and grounded itself on the header. I moved it off and the problem disappeared I'll be getting a new set of wires tomorrow.

Thanks
Zanethan