I have a 2004 Ford Ranger XLT with 4.0L V6, automatic trans, 90k miles. I figured out that in park/neutral the engine rev limits at 3k rpm. When driving Ive never really seen it go over 3,200 rpm and when it does it has a weird vibration. A couple days ago it almost made it to 4k rpm and didn’t want to shift. I hit the gas at a red light and was in a lane that would end soon so I had to get up to speed to make it in front of the car beside me. When I did that it went up to 4k, didn’t shift, and a second later shifted up 3 times in a row until it went down to 2k rpm and was fine after that (I had to get up to 55mph). When it’s at 4k it has a bad vibration (really anything over 2500 rpm it vibrates). Not sure why it’s doing that and why all of a sudden it wants to go up to 4k rpm.