I have a 01 Mit. Montero Limited & the engine is skipping?

the engine skipps during accelration and when ideling. I haven't replaced the plugs nor wires cause you have to take off the throttle body to do so. Do you think this is the problem? Hp is lost. Almost like it's running on 5cyl. Also, I get this huge vibration when driving at 2,000 rpm almost like its coming from the trans but it only does it at 2k. Could this also be the mis firing? How can I tell this is the problem without taking the throttle body off and such?