My 2000 Grand Cherokee has started to make a rumble and engine shaking once started. I thought it was only while taking off at first but it now has started even when idle. I first thought U joints but they and the CVs are good. It all started after I did an oil change and put in new spark plugs. I rechecked the plug gap and set them to .035. Has anyone else seen this before?
oh sorry this is 4.0L engine

 

You most likely knocked something like the crank sensor plug when changing the filter . Other wise make sure you got the correct firing order after doin the plugs . Maybe broke a lead when changing plugs ? .

 

I hope I understand what your saying about the plugs (but please forgive me if I'm wrong). I have the straight 6 4.0L that has a rail coil pack for my plugs, I did recently change the crank shaft sensor incase it was bad, as well as the transmission position sensor, transmission mount and fuel injectors, also put in a new fuel pump, im trying not to throw anymore unnecessary parts at it if possible. Any ideas why it's still doing this?