sounds like the timing is off just enough to set the fault. sometimes when you do a timing belt on these cars and you have the timing off just a tooth it will set a code, but still run fine. if its off a lot, itll cause it to run rough and set the code. if its off even worse, it could cause valve damage. but it sounds like yours might have just jumped time. set it on TDC and look at your mark at the crank and the mark at the cam gear.