93 Max was working fine yesterday. Today whenever it slows down or speeds up, generally under 55mph I feel a shuddering in the steering wheel. Can also kind of hear it coming from the engine.

Temperature is OK
RPM's are fine
No CEL
All other eletronic components fine such as radio, AC, etc.

Only change I made to it since yesterday was fill up with regular gas. I was at half a tank before, now at full tank. In VA we recently switched to an ethanol blend rather than a water blend to save the environment but I can't believe it's the gas!?

Any opinions??

 

Update: The EGR moves fine during acceleration. Just had a new tune up last year.

How would I test the spark plugs?? and or wires??

 

Park at a dark spot at night. Look under the hood for any sparks jumping off the plug wires. Depending on the mileage you should have changed wires by at least 90k or so. Spark plugs can be checked by pulling each one out in turn and examining the plug or by plugging out each cylinder one by one while the car is running and see if it makes any difference to the engine tone. If it does not change when you pulled a boot then you know that is the culprit.