if you have a rough idle after the t-belt was changed the timming is off. ohc engines that employ both a crank and cam position sensor are VERY sensitve to cam timming. if it's off by 1/2 tooth the eng will run like crap. the best way is to check timming by hand cranking the eng over 2-4 revs before reassy. that way you can see if the marks stay lined up, and you don't have to tear it back down to fix it, good luck.