I overheated my 2000 300m, blew the head gaskets/warped the heads. Had the machine shop check them out. They checked okay but had to milled them about 10 thou due to warpage.I put it all back together and now it has a rough idle, seems sluggish at takeoff, almost like you're taking off in 2nd gear, other than that, midrange and top end power are great. The check engine light came on, code said "system rich right bank". I checked all of the vacuum lines, fittings connectors, ect... can't find anything wrong. Now the check engine light went off by itself and still idles rough. Is it possible the timing belt is off one tooth on the passenger side, or would it not even run? I ask because I had to put the belt on 4 times before I got all the dots lined up correctly, the passenger cam kept moving one tooth when I put the tensioner on, but eventually I got it figured out. Even rotated the motor over a couple times via the crank bolt, and all the dots lined up. Any suggestions or help would be appreciated!