alright so i had this problem when driving on the freeway. once i would put the car in 6th gear and gas it to pick up a little speed the car would almost shake and i think it was the transmission shaking, but i ahve never had this problem before even when at a low rpm in 6th and gasing it. i was going around 65-75 and at about 2rpm's and had this problem then the check engine light started flashing (granted it had been on before this happened, dont really know what it is on for had it checked out and it was jsut something to pass smog i believe) but regardless it just seemed wierd, i did for the first time put synthetic in if that has anything to do with it.

Any ideas?

 

Check engine light generally "flashes" for engine misfires. Lugging at low RPM in 6th gear is one of the first places failing ignition components are going to show up.

 

Like Injuneer said, it sounds like your ignition system is misfiring. You might want to check your spark plugs to make sure they aren't fouling, and check all other small stuff like your Air/Fuel Filter, might want to check your fuel rail, and injectors to make sure everything is good. It doesn't sound to me like a transmission issue, sound like an ignition system as well.

--- Dax