Well my 97 V6 auto has been vibrating a bit around 49-50mph. Its just a slight shudder but starting to annoy me more and more. About a month ago when this started I swapped out the plugs and wires. The vibration went down a bit. Just yesterday I changed the oil, rear diff fluid, flushed the cooling system, replaced the fuel filter and had a fuel system clean (going to CA soon). The car runs a lot smoother but the slight shudder is still there at the same speed. With a little throttle or a release in the pedal the car will stop the shudder immediately. Im thinking it might be the o2 sensor but it only happens around the highway speeds. I tried a search already but most of these problems were with lt1s and the opti, some were o2 sensors. I have no codes displaying. Anyone have a clue of whats up?!? What should I do...TIA

 

Did you try checking ur tranny mount?

 

No, didnt think about that. I'll get it checked out. Is that expensive to replace?