Chugging at lights, slipping while pressing the gas etc....

Ok so when i am at a light....my idle will go down pretty low and start chugging and the whole care seems to shake...eventually the check engine light will come on. if i give it a little gas or put it in nutural then drive again it will be fine. The timing belt was changed about a year ish ago and the heads on the engine were warped or something so they replaced those (thank god it was under warrenty!) that fixed it for a little bit...and then it started doing the same thing AGAIN!!! so i went to auto zone and it said timing belt or cam shaft position sensor so since the timing belt was changed pretty recently we changed the cam shaft sensor... well on the freeway after sitting in traffic it fel like the car was skipping or losing power or something was slipping in it when i pressed on the gas. so i pulled over and turned off the car, turned it back on and it was fine!!! OMG i'm stuck!! now the engine light wont come back on so i can't get it checked. currently it's running really rough...but still running...i can kind of feel it slipping. ALSO the underbody is making a clunking sound...like struts or something moving around...i have no idea! please help! :)