Engine vibration under light throttle

[nmos]

My 92 Explorer has recently developed a vibration. I mainly notice it under light throttle around 2k rpm but I can sometimes feel it at idle as well. It feels like something out of balance but I can't rule out a partial misfire. The CEL isn't on. My plan is to pull each of the plugs and check that they look about the same and then pull the serpentine belt and check for a wobble in any of the pulleys. Any other ideas?

 

[the_don]

Add engine mounts and cooling fan to your list.

 

[2stroke]

A/C kicking on?

 

[natenkiki2004]

Transmission mount too? Mine's caked in ATF and while doing the motor mounts helped, there's still some odd shakiness every so often. ATF isn't good on rubber mounts and bushings.

 

[acschilling]

I was developing a vibration at low speeds, accompanied by an awful squeak, that ended up being rear u joints. Real smooth now

 

[nmos]

The engine and transmission mounts look good although it's tough to get a good look at the right (passenger) side mount. The fan and fan clutch are less than two years old and I don't see any major cracks or chunks missing from the fan.

I removed the belt and the only pulley that didn't spin smoothly was the power steering pump but I'm not sure how that one should feel. It isn't making that power steering whine yet but there is a bit of a squeak coming from that side of the engine when it's running.