I have an 01 explorer and when I drive between 25-35mph it shakes. Once i go above 35 it stops. Ive changed out the spark plugs but still does it. Anyone have any suggestions?

 

When you say shaking do you mean:
The whole vehicle shakes
The steering wheel shakes
The back end can feel in the seat, shakes
Just the motor shakes
Usually when it shakes as you describe , my first inclination is you could have a tire that is experiencing ply separation, but that is how we get in trouble making a call on skimpy info. Lets wait until you can provide more specific info.

 

I can feel the whole truck shake...ive been thinking maybe i need to balance my tires?

 

A tire imbalance condition could certainly yield the symptoms you are getting. Sometime a wheel weight will come off and leave the wheel in need of rebalancing.

 

Ok well i got the tires balanced and rotated...still shakes. I dont think its trans because rpm's arent going up out of the norm. I feel the the shake in my steering whell and the back window vibrate thats why i say the whole truck vibrates. It doesnt shake when in nuetral and i press on the pedal.

 

We are still doing this by description and the best way to diagnose this, is being there.
In order to help isolate the shaking, Do you get the same shaking if you had the trans shifter in D2 at that same 35 MPH ? The engine RPM will be higher, but we need to know if the engine speed or road speed is contributing to the problem.

 

The issue for the shakey truck was bad u-joint and bad pinions in front diff. Replaced the u-joint and because of the price to fix the diff i now have rear wheel drive ford explorer instead of 4x4 but now runs good!