I have a 2006 81,000 miles on it and while driving on the highway, the engine shutters/stutters between 1500 and 1800 RPMs to a point it feels like I’m hitting bumps after bumps on the road. When I get on the gas and get RPMs over 2000 she settles down and rides nice and smooth. I have changed the fuel filter, air filter, MAF and cleaned the throttle body.
Any advice will be great, Thanks in advance.

 

Have the plugs been changed?

 

Nope, been worried about the headache of them snapping.

 

That's what is causing it - and you are 21k past recommendation.

 

Ditto, low grade misfire. Your spark plugs need replacing. I just replaced my 2nd set due this exact problem. Good luck.