Engine vibrations in idle and overdrive
I have a 2000 3.0v6 Ranger FFV with 120k mi on it. One day several months ago, I backed out of my driveway and put it into drive, and when accellerating, I noticed a distinct vibration in the engine for the first 2 or 3 seconds of accelleration. It went away and I forgot about it. Yesterday, it came back, only now it vibrates both in idle and when the engine shifts into overdrive. If I'm at a stop light with my foot on the brake, it vibrates, and it also vibes for the first few seconds of accelleration, but then goes away. As soon at it shifts into OD around 50mph, the vibrations come back. I put the truck in park and it vibrates, and it also vibrates in neutral. But between 5 and 50 mph there are no vibrations. It is bad enough in OD that I have to turn the OD off and drive without it. Some guys I work with said to check the spark plugs or the throttle body, but they weren't sure. Since it vibrates in neutral, I'm guessing that it's not the transmission. I bought this truck used and have put 30k miles on it, but I have no idea what type of maintenance it received before me.
Any suggestions for the vibrations?
Thanks


